Engineering › Electrical and Electronic Engineering

Plasmonics for Photovoltaic Devices

Works Count: 68683

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Description

This cluster of papers focuses on the application of plasmonics and advanced semiconductor technologies to improve the efficiency and performance of photovoltaic devices. It covers topics such as plasmonic light trapping, transparent flexible thin-film transistors, oxide semiconductor materials, and solution-processed metal oxides for solar cells and electronics.

Keywords

Plasmonics; Thin-Film Transistors; Amorphous Oxide Semiconductors; Solar Cells; Light Trapping; Transparent Electronics; High-Mobility Transistors; Solution-Processed Metal Oxides; Nanoparticle Enhanced Absorption; Flexible Electronics

Light management for photovoltaics using high-index nanostructures

2014-04-22

Mark L. Brongersma , Yi Cui , Shanhui Fan

Design of Plasmonic Thin‐Film Solar Cells with Broadband Absorption Enhancements

2009-06-02

Ragip Pala , Justin S. White , Edward S. Barnard +2 more

Noble metal nanostructures can enhance absorption in thin-film solar cells by simultaneously taking advantage of i) high near-fields surrounding the nanostructures close to their surface plasmon resonance frequency and ii) … Noble metal nanostructures can enhance absorption in thin-film solar cells by simultaneously taking advantage of i) high near-fields surrounding the nanostructures close to their surface plasmon resonance frequency and ii) coupling to waveguide modes. We develop basic design rules for the realization of broadband absorption enhancements for such structures.

Reversible conductivity changes in discharge-produced amorphous Si

1977-08-15

D. L. Staebler , C. R. Wroński

A new reversible photoelectronic effect is reported for amorphous Si produced by glow discharge of SiH4. Long exposure to light decreases both the photoconductivity and the dark conductivity, the latter … A new reversible photoelectronic effect is reported for amorphous Si produced by glow discharge of SiH4. Long exposure to light decreases both the photoconductivity and the dark conductivity, the latter by nearly four orders of magnitude. Annealing above 150 °C reverses the process. A model involving optically induced changes in gap states is proposed. The results have strong implications for both the physical nature of the material and for its applications in thin-film solar cells, as well as the reproducibility of measurements on discharge-produced Si.

Material characteristics and applications of transparent amorphous oxide semiconductors

2010-01-01

Toshio Kamiya , Hideo Hosono

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Disorder and the Optical-Absorption Edge of Hydrogenated Amorphous Silicon

1981-11-16

George D. Cody , T. Tiedje , B. Abeles +2 more

The effect of thermal and structural disorder on the electronic structure of hydrogenated amorphous silicon is investigated by measurement of the shape of the optical absorption edge as a function … The effect of thermal and structural disorder on the electronic structure of hydrogenated amorphous silicon is investigated by measurement of the shape of the optical absorption edge as a function of temperature and thermal evolution of hydrogen. The data are consistent with the idea that the thermal and structural disorder are additive, and suggest that the disorder, rather than the hydrogen content, is the fundamental determining factor in the optical band gap.

Light-induced metastable defects in hydrogenated amorphous silicon: A systematic study

1985-07-01

M. Stutzmann , W. B. Jackson , C. C. Tsai

We study the magnitude of metastable light-induced changes in undoped hydrogenated amorphous silicon (the Staebler-Wronski effect) with electron-spin-resonance and photoconductivity measurements. The influence of the following parameters is investigated in … We study the magnitude of metastable light-induced changes in undoped hydrogenated amorphous silicon (the Staebler-Wronski effect) with electron-spin-resonance and photoconductivity measurements. The influence of the following parameters is investigated in a systematic way: sample thickness, impurity content, illumination time, light intensity, photon energy, and illumination and annealing temperatures. The experimental results can be explained quantitatively by a model based on the nonradiative recombination of photoexcited carriers as the defect-creating step. In the framework of this model, the Staebler-Wronski effect is an intrinsic, self-limiting bulk process, characterized by a strongly sublinear dependence on the total light exposure of a sample. The experimental results suggest that the metastable changes are caused by recombination-induced breaking of weak Si--Si bonds, rather than by trapping of excess carriers in already existing defects. Hydrogen could be involved in the microscopic mechanism as a stabilizing element. The main metastable defect created by prolonged illumination is the silicon dangling bond. An analysis of the annealing behavior shows that a broad distribution of metastable dangling bonds exists, characterized by a variation of the energy barrier separating the metastable state from the stable ground state between 0.9 and 1.3 eV.

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

2012-05-10

Elvira Fortunato , Pedro Barquinha , Rodrigo Martins

Abstract Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins … Abstract Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n‐ and p‐type oxide based thin‐film transistors (TFT) is reviewed, with special emphasis on solution‐processed and p‐type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n‐type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution‐processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p‐type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n‐ and p‐type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n‐ and p‐type oxide transistors as well as the fabrication of CMOS devices with and on paper.

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Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors

2004-11-01

Kenji Nomura , Hiromichi Ohta , Akihiro Takagi +3 more

Optical dispersion relations for amorphous semiconductors and amorphous dielectrics

1986-11-15

A. Rahim Forouhi , Iris Bloomer

An expression for the imaginary part, k, of the complex index of refraction, N=n-ik, for amorphous materials is derived as a function of photon energy E: k(E)=A(E-${E}_{g}$${)}^{2}$/(${E}^{2}$-BE+C) where A, B, … An expression for the imaginary part, k, of the complex index of refraction, N=n-ik, for amorphous materials is derived as a function of photon energy E: k(E)=A(E-${E}_{g}$${)}^{2}$/(${E}^{2}$-BE+C) where A, B, and C are positive nonzero constants characteristic of the medium such that 4C-${B}^{2}$>0. ${E}_{g}$ represents the optical energy band gap. The real part, n, of the complex index of refraction is then determined to be n(E)=n(\ensuremath{\infty})+(${B}_{0}$E+${C}_{0}$)/ (${E}^{2}$-BE+C) using Kramers-Kronig analysis, where ${B}_{0}$ and ${C}_{0}$ are constants that depend on A, B, C, and ${E}_{g}$, and n(\ensuremath{\infty}) is a constant greater than unity. Excellent agreement was found between these formulas and experimentally measured and published values of n and k of amorphous silicon, hydrogenated amorphous silicon, amorphous silicon nitride, and titanium dioxide.

Improved performance of amorphous silicon solar cells via scattering from surface plasmon polaritons in nearby metallic nanoparticles

2006-08-28

Daniel Derkacs , S. H. Lim , Peter Matheu +2 more

An engineered enhancement in short-circuit current density and energy conversion efficiency in amorphous silicon p-i-n solar cells is achieved via improved transmission of electromagnetic radiation arising from forward scattering by … An engineered enhancement in short-circuit current density and energy conversion efficiency in amorphous silicon p-i-n solar cells is achieved via improved transmission of electromagnetic radiation arising from forward scattering by surface plasmon polariton modes in Au nanoparticles deposited above the amorphous silicon film. For a Au nanoparticle density of ∼3.7×108cm−2, an 8.1% increase in short-circuit current density and an 8.3% increase in energy conversion efficiency are observed. Finite-element electromagnetic simulations confirm the expected increase in transmission of electromagnetic radiation at visible wavelengths, and suggest that substantially larger improvements should be attainable for higher nanoparticle densities.

Formation kinetics and control of microcrystallite in μc-Si:H from glow discharge plasma

1983-12-01

Akihisa Matsuda

The one phonon Raman spectrum in microcrystalline silicon

1981-08-01

H. Richter , Z. P. Wang , L. Ley

Theory of the field-effect mobility in amorphous organic transistors

1998-05-15

M. C. J. M. Vissenberg , M. Matters

The field-effect mobility in an organic thin-film transistor is studied theoretically. From a percolation model of hopping between localized states and a transistor model an analytic expression for the field-effect … The field-effect mobility in an organic thin-film transistor is studied theoretically. From a percolation model of hopping between localized states and a transistor model an analytic expression for the field-effect mobility is obtained. The theory is applied to describe the experiments by Brown et al. [Synth. Met. 88, 37 (1997)] on solution-processed amorphous organic transistors, made from a polymer (polythienylene vinylene) and from a small molecule (pentacene). Good agreement is obtained, with respect to both the gate voltage and the temperature dependence of the mobility.

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Review of recent developments in amorphous oxide semiconductor thin-film transistor devices

2011-07-16

Joon Seok Park , W. J. Maeng , Hyun‐Suk Kim +1 more

Kinetics of solid phase crystallization in amorphous silicon

1988-01-01

G. L. Olson , J. A. Roth

Electronic properties of substitutionally doped amorphous Si and Ge

1976-06-01

W. E. Spear , P. G. Le Comber

Abstract It is shown that substitutional doping of an amorphous semiconductor is possible and can provide control of the electronic properties over a wide range. a-Si and Ge specimens have … Abstract It is shown that substitutional doping of an amorphous semiconductor is possible and can provide control of the electronic properties over a wide range. a-Si and Ge specimens have been prepared by the decomposition of silane (or germane) in a radio-frequency (r.f.) glow discharge. Doping is achieved by adding carefully measured amounts of phosphine or diborane, between 5 × 10−6 and 10−2 parts per volume, to obtain n- or p-type specimens. The room temperature conductivity of doped a-Si specimens can be controlled reproducibly over about 10 orders of magnitude, which corresponds to a movement of the Fermi level of 1·2 eV. Ion probe analysis on phosphorus doped specimens indicates that about half the phosphine molecules in the gaseous mixture introduce a phosphorus atom into the Si random network; it is estimated that 30–40% of these will act as substitutional donors. The results also show that the number of incorporated phosphorus atoms saturates at about 3 × 1019 cm−3, roughly equal to the number of states in the band tail. It is suggested that, in general, donor sites lie within the energy range of the electron tail states. The use of doped specimens in field effect measurements has considerably extended the range of the experimentally determined density of state function and new results are presented. It is concluded that the main material requirement for effective doping in an amorphous semiconductor is a very low overall density of gap states; in this respect evaporated or sputtered films are far less suitable than glow discharge specimens.

High-mobility thin-film transistor with amorphous InGaZnO4 channel fabricated by room temperature rf-magnetron sputtering

2006-09-11

Hisato Yabuta , Masafumi Sano , Katsumi Abe +6 more

Thin-film transistors (TFTs) were fabricated using amorphous indium gallium zinc oxide (a-IGZO) channels by rf-magnetron sputtering at room temperature. The conductivity of the a-IGZO films was controlled from ∼10−3to10−6Scm−1 by … Thin-film transistors (TFTs) were fabricated using amorphous indium gallium zinc oxide (a-IGZO) channels by rf-magnetron sputtering at room temperature. The conductivity of the a-IGZO films was controlled from ∼10−3to10−6Scm−1 by varying the mixing ratio of sputtering gases, O2∕(O2+Ar), from ∼3.1% to 3.7%. The top-gate-type TFTs operated in n-type enhancement mode with a field-effect mobility of 12cm2V−1s−1, an on-off current ratio of ∼108, and a subthreshold gate voltage swing of 0.2Vdecade−1. It is demonstrated that a-IGZO is an appropriate semiconductor material to produce high-mobility TFTs at low temperatures applicable to flexible substrates by a production-compatible means.

Structural interpretation of the vibrational spectra of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>a</mml:mi></mml:math>-Si: H alloys

1979-02-15

G. Lucovsky , R. J. Nemanich , J. C. Knights

The ir and Raman spectra of $a$-Si: H alloys produced by plasma decomposition of Si${\mathrm{H}}_{4}$ are studied for a wide range of deposition conditions. The vibrational spectra display modes which … The ir and Raman spectra of $a$-Si: H alloys produced by plasma decomposition of Si${\mathrm{H}}_{4}$ are studied for a wide range of deposition conditions. The vibrational spectra display modes which can be characterized as predominantly hydrogen motions. Analysis of these modes shows four types of local Si-H bonding environments which are identified as SiH, Si${\mathrm{H}}_{2}$, Si${\mathrm{H}}_{3}$, and coupled Si${\mathrm{H}}_{2}$ or ${(\mathrm{Si}{\mathrm{H}}_{2})}_{n}$ units. On the basis of these identifications, it is found that samples produced on high-temperature (above 200\ifmmode^\circ\else\textdegree\fi{}C) substrates have SiH, Si${\mathrm{H}}_{2}$, and ${(\mathrm{Si}{\mathrm{H}}_{2})}_{n}$ groups with very little Si${\mathrm{H}}_{3}$. In contrast, the ir and Raman spectra of samples produced on room-temperature or cooled substrates are dominated by vibrational modes of Si${\mathrm{H}}_{3}$ and ${(\mathrm{Si}{\mathrm{H}}_{2})}_{n}$. The relative concentrations of these hydrogen-containing groups are not simply proportional to the total hydrogen concentration in a given sample.

Amorphous Oxide Semiconductors for High-Performance Flexible Thin-Film Transistors

2006-05-01

Kenji Nomura , Akihiro Takagi , Toshio Kamiya +3 more

Recently, we have demonstrated the potential of amorphous oxide semiconductors (AOSs) for developing flexible thin-film transistors (TFTs). A material exploration of AOSs desired as the channel layer in TFTs is … Recently, we have demonstrated the potential of amorphous oxide semiconductors (AOSs) for developing flexible thin-film transistors (TFTs). A material exploration of AOSs desired as the channel layer in TFTs is most important for developing high-performance devices. Here, we report our concept of material exploration for AOSs in high-performance flexible and transparent TFTs from the viewpoints of chemical bonding and electronic structure in oxide semiconductors. We find that amorphous In–Ga–Zn–O (a-IGZO) exhibits good carrier transport properties such as reasonably high Hall mobilities (>10 cm2·V-1·s-1) and a good controllability of carrier concentration from <1015 to 1020 cm-3. In addition, a-IGZO films have better chemical stabilities in ambient atmosphere and at temperatures up to 500 °C. The flexible and transparent TFT fabricated using a-IGZO channel layer at room temperature operated with excellent performances, such as normally-off characteristics, on/off current ratios (∼106) and field-effect mobilities (∼10 cm2·V-1·s-1), which are higher by an order of magnitude than those of amorphous Si:H and organics TFTs.

Optically induced conductivity changes in discharge-produced hydrogenated amorphous silicon

1980-06-01

D. L. Staebler , C. R. Wroński

Long exposure to light decreases the photoconductivity and dark conductivity of some samples of hydrogenated amorphous silicon (a-Si : H). Annealing above ∼150 °C reverses the process. The effect occurs … Long exposure to light decreases the photoconductivity and dark conductivity of some samples of hydrogenated amorphous silicon (a-Si : H). Annealing above ∼150 °C reverses the process. The effect occurs in the bulk of the films, and is associated with changes in density or occupation of deep gap states. High concentrations of P, B, or As quench the effect. Possible models involving hydrogen bond reorientation at a localized defect or electron-charge transfer between defects are discussed. An example is shown where these conductivity changes do not affect the efficiency of an a-Si : H solar cell.

Infrared spectroscopic study of SiOx films produced by plasma enhanced chemical vapor deposition

1986-05-01

P. G. Pai , S. S. Chao , Yasuo Takagi +1 more

We have studied the local atomic structure of silicon suboxide (SiOx, x&lt;2) thin films using infrared (IR) spectroscopy. The films were prepared by plasma enhanced chemical vapor deposition (PECVD) of … We have studied the local atomic structure of silicon suboxide (SiOx, x&lt;2) thin films using infrared (IR) spectroscopy. The films were prepared by plasma enhanced chemical vapor deposition (PECVD) of silane (SiH4) and nitrous oxide (N2O) mixtures, which were then diluted with He. The IR spectra were found to vary significantly with the degree of He dilution. Films grown with no He showed SiN, NH, and SiH bonding groups in addition to the three characteristic vibrations of the Si–O–Si linkage. The addition of He reduced the strength of the SiN, NH, and SiH absorption bands, and resulted in systematic increases in the frequency of the Si–O–Si asymmetric stretching vibration. The frequency of this Si–O–Si stretching vibration scales linearly with the oxygen concentration from approximately 940 cm−1 in oxygen doped amorphous silicon to 1075 cm−1 in stoichiometric noncrystalline SiO2. A deposition temperature of 350 °C and a He dilution of 50% gave a film composition close to SiO1.9. We propose a model for the deposition process that emphasizes the role of the He dilution.

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Ionic amorphous oxide semiconductors: Material design, carrier transport, and device application

2006-04-05

Hideo Hosono

Plasmonic solar cells

2008-12-17

Kylie Catchpole , Albert Polman

The scattering from metal nanoparticles near their localized plasmon resonance is a promising way of increasing the light absorption in thin-film solar cells.Enhancements in photocurrent have been observed for a … The scattering from metal nanoparticles near their localized plasmon resonance is a promising way of increasing the light absorption in thin-film solar cells.Enhancements in photocurrent have been observed for a wide range of semiconductors and solar cell configurations.We review experimental and theoretical progress that has been made in recent years, describe the basic mechanisms at work, and provide an outlook on future prospects in this area.

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Optical Properties and Electronic Structure of Amorphous Germanium

1966-01-01

J. Tauc , R. Grigorovici , A. Vancu

Abstract The optical constants of amorphous Ge are determined for the photon energies from 0.08 to 1.6 eV. From 0.08 to 0.5 eV, the absorption is due to k ‐conserving … Abstract The optical constants of amorphous Ge are determined for the photon energies from 0.08 to 1.6 eV. From 0.08 to 0.5 eV, the absorption is due to k ‐conserving transitions of holes between the valence bands as in p‐type crystals; the spin‐orbit splitting is found to be 0.20 and 0.21 eV in non‐annealed, and annealed samples respectively. The effective masses of the holes in the three bands are 0.49 m (respectively 0.43 m ); 0.04 m , and 0.08 m . An absorption band is observed below the main absorption edge (at 300 °K the maximum of this band is at 0.86 eV); the absorption in this band increases with increasing temperature. This band is considered to be due to excitons bound to neutral acceptors, and these are presumably the same ones that play a decisive role in the transport properties and which are considered to be associated with vacancies. The absorption edge has the form: ω 2 ϵ 2 ∼(hω− E g ) 2 ( E g = 0.88 eV at 300 °K). This suggests that the optical transitions conserve energy but not k vector, and that the densities of states near the band extrema have the same energy‐dependence as in crystalline Ge. A simple theory describing this situation is proposed, and comparison of it with the experimental results leads to an estimate of the localization of the conduction‐band wavefunctions.

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Tunable near-infrared and visible-light transmittance in nanocrystal-in-glass composites

2013-08-01

Anna Llordés , Guillermo García , Jaume Gázquez +1 more

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Photovoltaic Technology: The Case for Thin-Film Solar Cells

1999-07-30

A. Shah , P. Torres , R. Tscharner +2 more

The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and … The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and the associated fabrication technologies are individually described, emphasis is on silicon-based solar cells. Wafer-based crystalline silicon solar modules dominate in terms of production, but amorphous silicon solar cells have the potential to undercut costs owing, for example, to the roll-to-roll production possibilities for modules. Recent developments suggest that thin-film crystalline silicon (especially microcrystalline silicon) is becoming a prime candidate for future photovoltaics.

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Fully Transparent ZnO Thin‐Film Transistor Produced at Room Temperature

2005-03-03

Elvira Fortunato , Pedro Barquinha , Ana Pimentel +4 more

Fully transparent thin-film transistors (TFTs) are produced at room temperature by radiofrequency magnetron sputtering. Measuring the drain current (IDS) as a function of drain voltage (VDS) at different gate voltages … Fully transparent thin-film transistors (TFTs) are produced at room temperature by radiofrequency magnetron sputtering. Measuring the drain current (IDS) as a function of drain voltage (VDS) at different gate voltages (VGS) shows the TFTs possess "hard saturation" with on-currents of about 0.2 mA (see Figure) and saturation mobilities of 20 cm2 V–1 s–1. The optical and electrical properties and the compatibility of the fabrication process with low-cost plastic substrates show promise for invisible and flexible electronic circuits.

High mobility transparent thin-film transistors with amorphous zinc tin oxide channel layer

2004-12-23

Hai Q. Chiang , John F. Wager , Randy Hoffman +2 more

Transparent thin-film transistors (TTFTs) with an amorphous zinc tin oxide channel layer formed via rf magnetron sputter deposition are demonstrated. Field-effect mobilities of 5–15 and 20–50cm2V−1s−1 are obtained for devices … Transparent thin-film transistors (TTFTs) with an amorphous zinc tin oxide channel layer formed via rf magnetron sputter deposition are demonstrated. Field-effect mobilities of 5–15 and 20–50cm2V−1s−1 are obtained for devices post-deposition annealed at 300 and 600°C, respectively. TTFTs processed at 300 and 600°C yield devices with turn-on voltage of 0–15 and −5–5V, respectively. Under both processing conditions, a drain current on-to-off ratio greater than 107 is obtained. Zinc tin oxide is one example of a new class of high performance TTFT channel materials involving amorphous oxides composed of heavy-metal cations with (n−1)d10ns0 (n⩾4) electronic configurations.

Design principles for particle plasmon enhanced solar cells

2008-11-10

Kylie Catchpole , Albert Polman

We develop fundamental design principles for increasing the efficiency of solar cells using light trapping by scattering from metal nanoparticles. We show that cylindrical and hemispherical particles lead to much … We develop fundamental design principles for increasing the efficiency of solar cells using light trapping by scattering from metal nanoparticles. We show that cylindrical and hemispherical particles lead to much higher path length enhancements than spherical particles, due to enhanced near-field coupling, and that the path length enhancement for an electric point dipole is even higher than the Lambertian value. Silver particles give much higher path length enhancements than gold particles. The scattering cross section of the particles is very sensitive to the thickness of a spacer layer at the substrate, which provides additional tunability in the design of particle arrays.

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Origin of threshold voltage instability in indium-gallium-zinc oxide thin film transistors

2008-09-22

Jae Kyeong Jeong , Hui Yang , Jong Han Jeong +2 more

We investigated the impact of the passivation layer on the stability of indium-gallium-zinc oxide (IGZO) thin film transistors. While the device without any passivation layer showed a huge threshold voltage … We investigated the impact of the passivation layer on the stability of indium-gallium-zinc oxide (IGZO) thin film transistors. While the device without any passivation layer showed a huge threshold voltage (Vth) shift under positive gate voltage stress, the suitably passivated device did not exhibit any Vth shift. The charge trapping model, which has been believed to be a plausible mechanism, cannot by itself explain this behavior. Instead, the Vth instability was attributed to the interaction between the exposed IGZO backsurface and oxygen and/or water in the ambient atmosphere during the gate voltage stress.

Low-temperature, high-performance solution-processed metal oxide thin-film transistors formed by a ‘sol–gel on chip’ process

2010-12-12

K.K. Banger , Y. Yamashita , K. Mori +4 more

Transparent Electronics

2003-05-22

John F. Wager

Effect of the annealing temperature on structural, morphological, and nonlinear optical properties of TeO 2 thin films used for efficient THz generation , Effect of the annealing temperature on structural, morphological, and nonlinear optical properties of TeO 2 thin films used for efficient THz generation ,

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Growth of native oxide on a silicon surface

1990-08-01

Mizuho Morita , T. Ohmi , Eiji Hasegawa +2 more

The control factors controlling the growth of native silicon oxide on silicon (Si) surfaces have been identified. The coexistence of oxygen and water or moisture is required for growth of … The control factors controlling the growth of native silicon oxide on silicon (Si) surfaces have been identified. The coexistence of oxygen and water or moisture is required for growth of native oxide both in air and in ultrapure water at room temperature. Layer-by-layer growth of native oxide films occurs on Si surfaces exposed to air. Growth of native oxides on n-Si in ultrapure water is described by a parabolic law, while the native oxide film thickness on n+-Si in ultrapure water saturates at 10 Å. The native oxide growth on n-Si in ultrapure water is continuously accompanied by a dissolution of Si into the water and degrades the atomic flatness at the oxide-Si interface, producing a rough oxide surface. A dissolution of Si into the water has not been observed for the Si wafer having surface covered by the native oxide grown in air. Native oxides grown in air and in ultrapure de-ionized water have been demonstrated experimentally to exhibit remarkable differences such as contact angles of ultrapure water drops and chemical binding energy. These chemical bond structures for native oxide films grown in air and in ultrapure water are also discussed.

Absorption edge and internal electric fields in amorphous semiconductors

1970-08-01

J. Tauc

Transparent Conducting Oxides for Photovoltaics

2007-03-01

Elvira Fortunato , David S. Ginley , Hideo Hosono +1 more

TCO and light trapping in silicon thin film solar cells

2004-04-21

J. Müller , B. Rech , Jiri Springer +1 more

Thin‐film silicon solar cell technology

2004-03-01

A. Shah , H. Schade , M. Vaněček +6 more

Abstract This paper describes the use, within p – i – n ‐ and n – i – p ‐type solar cells, of hydrogenated amorphous silicon (a‐Si:H) and hydrogenated microcrystalline … Abstract This paper describes the use, within p – i – n ‐ and n – i – p ‐type solar cells, of hydrogenated amorphous silicon (a‐Si:H) and hydrogenated microcrystalline silicon (μc‐Si:H) thin films (layers), both deposited at low temperatures (200°C) by plasma‐assisted chemical vapour deposition (PECVD), from a mixture of silane and hydrogen. Optical and electrical properties of the i ‐layers are described. These properties are linked to the microstructure and hence to the i ‐layer deposition rate, that in turn, affects throughput in production. The importance of contact and reflection layers in achieving low electrical and optical losses is explained, particularly for the superstrate case. Especially the required properties for the transparent conductive oxide (TCO) need to be well balanced in order to provide, at the same time, for high electrical conductivity (preferably by high electron mobility), low optical absorption and surface texture (for low optical losses and pronounced light trapping). Single‐junction amorphous and microcrystalline p – i – n ‐type solar cells, as fabricated so far, are compared in their key parameters ( J sc , FF, V oc ) with the [theoretical] limiting values. Tandem and multijunction cells are introduced; the μc‐Si: H/a‐Si: H or [micromorph] tandem solar cell concept is explained in detail, and recent results obtained here are listed and commented. Factors governing the mass‐production of thin‐film silicon modules are determined both by inherent technical reasons, described in detail, and by economic considerations. The cumulative effect of these factors results in distinct efficiency reductions from values of record laboratory cells to statistical averages of production modules. Finally, applications of thin‐film silicon PV modules, especially in building‐integrated PV (BIPV) are shown. In this context, the energy yields of thin‐film silicon modules emerge as a valuable gauge for module performance, and compare very favourably with those of other PV technologies. Copyright © 2004 John Wiley & Sons, Ltd.

Pentacene thin film transistors on inorganic dielectrics: Morphology, structural properties, and electronic transport

2002-12-28

Dietmar Knipp , R. A. Street , A. R. Völkel +1 more

The structural and transport properties of evaporated pentacene organic thin film transistors (TFTs) are reported, and they show the influence of the deposition conditions with different inorganic dielectrics. Dielectrics compatible … The structural and transport properties of evaporated pentacene organic thin film transistors (TFTs) are reported, and they show the influence of the deposition conditions with different inorganic dielectrics. Dielectrics compatible with large area fabrication were explored to facilitate low cost electronics on glass or flexible plastic substrates. X-ray diffraction and atomic force microscopy show a clear correlation between the morphology and the structure of the highly polycrystalline films for all dielectrics investigated. The roughness of the dielectric has a distinct influence on the morphology and the structural properties, whereas the films on smooth thermal oxide are in general highly ordered and independent of the deposition conditions. The ordered films exhibit a “thin film” and a bulk phase, and the bulk phase volume fraction increases with the deposition temperature and the film thickness. Careful control of the deposition conditions gives virtually identical films on thermal oxide and silicon nitride dielectrics. The electronic properties of inverted staggered transistors show that the TFT mobility is correlated with the morphology and structure of the films. The TFTs exhibit very similar mobilities of ∼0.4 cm2/Vs and on/off ratios &gt;108 on thermal oxide and silicon nitride. The impact of the dielectric on the device parameters of mobility, threshold voltage, and subthreshold voltage slope is discussed. Temperature dependent measurements of the mobility were performed to study the influence of traps on electronic transport. Bias stress experiments were carried out to investigate the stability of the TFTs, and to gain understanding of the transport mechanisms of thermally evaporated pentacene TFTs.

Infrared and Raman spectra of the silicon-hydrogen bonds in amorphous silicon prepared by glow discharge and sputtering

1977-10-15

M. H. Brodsky , M. Cardona , J. J. Cuomo

We have studied the number and nature of the silicon-hydrogen bonds in amorphous silicon films prepared in plasmas either of silane or of hydrogen and argon. The films from silane … We have studied the number and nature of the silicon-hydrogen bonds in amorphous silicon films prepared in plasmas either of silane or of hydrogen and argon. The films from silane glow discharges have qualitatively different Raman and infrared spectra which depend on deposition parameters such as substrate temperature and silane gas pressure. Three main groups of spectral bands are seen associated with the Si-H bonds: the Si-H bond stretch bands, the bands due to relative bending of two or three Si-H bonds with a common silicon atom, and the "wagging" bands of Si-H bonds with respect to the Si matrix. These bands are split in a way suggestive of the presence of SiH, Si${\mathrm{H}}_{2}$, and Si${\mathrm{H}}_{3}$ complexes: the bond-bending bands are absent when only SiH bonds are present. All three types of complexes are identified in films deposited from glow discharges of silane at pressures \ensuremath{\sim} 1 Torr and room temperature. Higher substrate temperatures and/or lower pressures reduce the Si${\mathrm{H}}_{2}$ and Si${\mathrm{H}}_{3}$ concentrations: films deposited at 250\ifmmode^\circ\else\textdegree\fi{}C and 0.1 Torr contain only SiH groups. From the strength of the corresponding absorption bands, H concentrations as high as 35 to 52 atomic percent are estimated. Films sputtered at 200\ifmmode^\circ\else\textdegree\fi{}C in a 10% ${\mathrm{H}}_{2}$-90% Ar mixture contain all three groupings observed in the silane-derived samples. Deuterated sputtered films are used to confirm the analysis. The first- and second-order Raman scattering spectra of the Si-Si bonds in pure and hydrogenated $a\ensuremath{-}\mathrm{S}\mathrm{i}$ are also discussed. The scattering efficiency of $a\ensuremath{-}\mathrm{S}\mathrm{i}$ is found to be as much as 10 times that of crystal Si. The depolarization ratio of the $a\ensuremath{-}\mathrm{S}\mathrm{i}$ Raman spectrum has been remeasured. Finally, a picture is presented of when it is appropriate to refer to heavily hydrogenated $a\ensuremath{-}\mathrm{S}\mathrm{i}$ as still being a material describable by $a\ensuremath{-}\mathrm{S}\mathrm{i}$ network models.

Design Considerations for Plasmonic Photovoltaics

2010-09-02

Vivian E. Ferry , Jeremy N. Munday , Harry A. Atwater

Abstract This paper reviews the recent research progress in the incorporation of plasmonic nanostructures with photovoltaic devices and the potential for surface plasmon enhanced absorption. We first outline a variety … Abstract This paper reviews the recent research progress in the incorporation of plasmonic nanostructures with photovoltaic devices and the potential for surface plasmon enhanced absorption. We first outline a variety of cell architectures incorporating metal nanostructures. We then review the experimental fabrication methods and measurements to date, as well as systematic theoretical studies of the optimal nanostructure shapes. Finally we discuss photovoltaic absorber materials that could benefit from surface plasmon enhanced absorption.

Flexible metal-oxide devices made by room-temperature photochemical activation of sol–gel films

2012-09-01

Yong‐Hoon Kim , Jae Sang Heo , Tae-Hyeong Kim +7 more

Present status of amorphous In–Ga–Zn–O thin-film transistors

2010-02-01

Toshio Kamiya , Kenji Nomura , Hideo Hosono

The present status and recent research results on amorphous oxide semiconductors (AOSs) and their thin-film transistors (TFTs) are reviewed. AOSs represented by amorphous In-Ga-Zn-O (a-IGZO) are expected to be the … The present status and recent research results on amorphous oxide semiconductors (AOSs) and their thin-film transistors (TFTs) are reviewed. AOSs represented by amorphous In-Ga-Zn-O (a-IGZO) are expected to be the channel material of TFTs in next-generation flat-panel displays because a-IGZO TFTs satisfy almost all the requirements for organic light-emitting-diode displays, large and fast liquid crystal and three-dimensional (3D) displays, which cannot be satisfied using conventional silicon and organic TFTs. The major insights of this review are summarized as follows. (i) Most device issues, such as uniformity, long-term stability against bias stress and TFT performance, are solved for a-IGZO TFTs. (ii) A sixth-generation (6G) process is demonstrated for 32″ and 37″ displays. (iii) An 8G sputtering apparatus and a sputtering target have been developed. (iv) The important effect of deep subgap states on illumination instability is revealed. (v) Illumination instability under negative bias has been intensively studied, and some mechanisms are proposed. (vi) Degradation mechanisms are classified into back-channel effects, the creation of traps at an interface and in the gate insulator, and the creation of donor states in annealed a-IGZO TFTs by the Joule heating; the creation of bulk defects should also be considered in the case of unannealed a-IGZO TFTs. (vii) Dense passivation layers improve the stability and photoresponse and are necessary for practical applications. (viii) Sufficient knowledge of electronic structures and electron transport in a-IGZO has been accumulated to construct device simulation models.

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Fundamental limit of nanophotonic light trapping in solar cells

2010-09-27

Zongfu Yu , Aaswath P. Raman , Shanhui Fan

Establishing the fundamental limit of nanophotonic light-trapping schemes is of paramount importance and is becoming increasingly urgent for current solar cell research. The standard theory of light trapping demonstrated that … Establishing the fundamental limit of nanophotonic light-trapping schemes is of paramount importance and is becoming increasingly urgent for current solar cell research. The standard theory of light trapping demonstrated that absorption enhancement in a medium cannot exceed a factor of 4 n 2 / sin 2 θ , where n is the refractive index of the active layer, and θ is the angle of the emission cone in the medium surrounding the cell. This theory, however, is not applicable in the nanophotonic regime. Here we develop a statistical temporal coupled-mode theory of light trapping based on a rigorous electromagnetic approach. Our theory reveals that the conventional limit can be substantially surpassed when optical modes exhibit deep-subwavelength-scale field confinement, opening new avenues for highly efficient next-generation solar cells.

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Optical Absorption Enhancement in Amorphous Silicon Nanowire and Nanocone Arrays

2008-12-10

Jia Zhu , Zongfu Yu , George F. Burkhard +7 more

Hydrogenated amorphous Si (a-Si:H) is an important solar cell material. Here we demonstrate the fabrication of a-Si:H nanowires (NWs) and nanocones (NCs), using an easily scalable and IC-compatible process. We … Hydrogenated amorphous Si (a-Si:H) is an important solar cell material. Here we demonstrate the fabrication of a-Si:H nanowires (NWs) and nanocones (NCs), using an easily scalable and IC-compatible process. We also investigate the optical properties of these nanostructures. These a-Si:H nanostructures display greatly enhanced absorption over a large range of wavelengths and angles of incidence, due to suppressed reflection. The enhancement effect is particularly strong for a-Si:H NC arrays, which provide nearly perfect impedance matching between a-Si:H and air through a gradual reduction of the effective refractive index. More than 90% of light is absorbed at angles of incidence up to 60 degrees for a-Si:H NC arrays, which is significantly better than NW arrays (70%) and thin films (45%). In addition, the absorption of NC arrays is 88% at the band gap edge of a-Si:H, which is much higher than NW arrays (70%) and thin films (53%). Our experimental data agree very well with simulation. The a-Si:H nanocones function as both absorber and antireflection layers, which offer a promising approach to enhance the solar cell energy conversion efficiency.

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Ultra-high mobility transparent organic thin film transistors grown by an off-centre spin-coating method

2014-01-08

Yongbo Yuan , Gaurav Giri , Alexander L. Ayzner +7 more

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Metal oxides for optoelectronic applications

2016-03-23

Xinge Yu , Tobin J. Marks , Antonio Facchetti

High-k Gate Dielectrics for Emerging Flexible and Stretchable Electronics

2018-05-22

Binghao Wang , Wei Huang , Lifeng Chi +3 more

Recent advances in flexible and stretchable electronics (FSE), a technology diverging from the conventional rigid silicon technology, have stimulated fundamental scientific and technological research efforts. FSE aims at enabling disruptive … Recent advances in flexible and stretchable electronics (FSE), a technology diverging from the conventional rigid silicon technology, have stimulated fundamental scientific and technological research efforts. FSE aims at enabling disruptive applications such as flexible displays, wearable sensors, printed RFID tags on packaging, electronics on skin/organs, and Internet-of-things as well as possibly reducing the cost of electronic device fabrication. Thus, the key materials components of electronics, the semiconductor, the dielectric, and the conductor as well as the passive (substrate, planarization, passivation, and encapsulation layers) must exhibit electrical performance and mechanical properties compatible with FSE components and products. In this review, we summarize and analyze recent advances in materials concepts as well as in thin-film fabrication techniques for high-k (or high-capacitance) gate dielectrics when integrated with FSE-compatible semiconductors such as organics, metal oxides, quantum dot arrays, carbon nanotubes, graphene, and other 2D semiconductors. Since thin-film transistors (TFTs) are the key enablers of FSE devices, we discuss TFT structures and operation mechanisms after a discussion on the needs and general requirements of gate dielectrics. Also, the advantages of high-k dielectrics over low-k ones in TFT applications were elaborated. Next, after presenting the design and properties of high-k polymers and inorganic, electrolyte, and hybrid dielectric families, we focus on the most important fabrication methodologies for their deposition as TFT gate dielectric thin films. Furthermore, we provide a detailed summary of recent progress in performance of FSE TFTs based on these high-k dielectrics, focusing primarily on emerging semiconductor types. Finally, we conclude with an outlook and challenges section.

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Amorphous silicon solar cell

1976-06-01

David Carlson , C. R. Wroński

Thin film solar cells, ∼1 μm thick, have been fabricated from amorphous silicon deposited from a glow discharge in silane. The cells were made in a p-i-n structure by using … Thin film solar cells, ∼1 μm thick, have been fabricated from amorphous silicon deposited from a glow discharge in silane. The cells were made in a p-i-n structure by using doping gases in the discharge. The best power conversion efficiency to date is 2.4% in AM-1 sunlight. The maximum efficiency of thin-film amorphous silicon solar cells is estimated to be ∼14–15%.

Amorphous and Liquid Semiconductors

1974-01-01

J. Tauc

Improvement in Memory Operation of 2T0C DRAM Cells via Double-Layered InGaZnO Active Channel and Geometry Modulation

2025-06-26

Sang Han Ko , Sung‐Min Yoon | Electronic Materials Letters

Retraction Note: Structural, optical and electrical characterization of vacuum-evaporated nanocrystalline CdSe thin films for photosensor applications

2025-06-26

Vipin Kumar , Aditya Sharma , Kapil Sharma +1 more | Applied Physics A

Paper-Based Flexible UV Radiation Monitoring Devices with an IGZO Sensing Layer for Wearable Electronics

2025-06-24

R. K. Singh , Monika Gadhewal , Sourav Maity +1 more | ACS Applied Electronic Materials

Tailoring Hydrogenation to Enhance Defect Suppression and Charge Transport in Hydrogenated Amorphous Silicon for Flexible Photodetectors

2025-06-23

Y. Jeong , K. Hyun , Hyungil Jang +5 more | Advanced Science

Visible-light photodetectors (VPDs) garner significant attention due to their diverse applications in optical communication. However, conventional VPDs struggle to achieve both transparency and flexibility, limiting their use in emerging technologies. … Visible-light photodetectors (VPDs) garner significant attention due to their diverse applications in optical communication. However, conventional VPDs struggle to achieve both transparency and flexibility, limiting their use in emerging technologies. Hydrogenated amorphous silicon (a-Si:H) offers a promising platform for flexible optoelectronics for compatibility with substrates, although temperature reduction causes degradation of electrical and optical properties due to insufficient hydrogen passivation. In this study, the effect of the hydrogen-to-silane (H2/SiH4; f ratio) gas is systematically investigated ratio on the microstructural, optical, and electrical properties of a-Si:H films synthesized at an ultra-low temperature of 90 °C using plasma-enhanced chemical vapor deposition (PECVD). Raman and Fourier-transform infrared (FT-IR) spectroscopy reveal that an optimized H2/SiH4 ratio minimizes Si─H2 bonding, effectively reducing defect density and improving film stability. Spectroscopic ellipsometry confirms that this ratio optimizes the refractive index and optical bandgap, enhancing light absorption. Electrical measurements demonstrate that photodiodes with the optimized a-Si:H layer exhibit superior photosensitivity and suppressed dark current (f2: 20.6 and f8: 2.70 × 10-10 A, respectively), attributed to improved carrier transport and reduced Shockley-Read-Hall (SRH) recombination. Furthermore, flexible photodetectors maintain high mechanical reliability under repeated bending cycles. These findings highlight the potential of ultra-low-temperature PECVD a-Si:H films for high-performance, flexible photodetectors.

Enhancing the performance in p-type SnO TFTs through SiC co-sputtering and oxygen vacancy control

2025-06-21

Rauf Khan , Abdullah Al Moyeen , A.B.M.O. Islam +4 more | Materials Science in Semiconductor Processing

Plasmonic printing of high-performance metal oxide electronics under room temperature

2025-06-19

Zhan Gao , Yang Fu , Qiang Zhang +7 more | Nature Materials

Optical Properties of a-SiC:H Thin Films Deposited by Magnetron Sputtering

2025-06-18

Christina Veneti , L. Magafas , Panagiota Papadopoulou | Electronic Materials

In the present work a-SiC:H thin films were prepared using magnetron sputtering technique for different substrate temperatures from 100 °C to 290 °C. Their optical properties were studied using the … In the present work a-SiC:H thin films were prepared using magnetron sputtering technique for different substrate temperatures from 100 °C to 290 °C. Their optical properties were studied using the ellipsometry technique. The experimental results show that the optical band gap of the films varies from 2.00 eV to 2.18 eV for the hydrogenated films, whereas the Eg is equal to 1.29 eV when the film does not contain hydrogen atoms and for Ts = 100 °C. The refractive index has been observed to remain stable in the region of 100 °C–220 °C, whereas it drops significantly when the temperature of 290 °C is reached. Additionally, the refractive index exhibits an inverse relationship with Eg as a function of Ts. Notably, these thin films were deposited 12 years ago, and their optical properties have remained stable since then.

Unveiling Thickness-Dependent Oxidation Effect on Optical Response of Room Temperature RF-Sputtered Nickel Ultrathin Films on Amorphous Glass: An Experimental and FDTD Investigation

2025-06-18

Dylan A. Huerta-Arteaga , M. A. Ruiz-Robles , Srivathsava Surabhi +7 more | Materials

Nickel (Ni) ultrathin films exhibit phase-dependent electrical, magnetic, and optical characteristics that are significantly influenced by deposition methods. However, these films are inherently prone to rapid oxidation, with the oxidation … Nickel (Ni) ultrathin films exhibit phase-dependent electrical, magnetic, and optical characteristics that are significantly influenced by deposition methods. However, these films are inherently prone to rapid oxidation, with the oxidation rate dependent on substrate, temperature, and deposition parameters. The focus of this research is to investigate the temporal oxidation of RF-sputtered Ni ultrathin films on Corning glass under ambient atmospheric conditions and its impact on their structural, surface, and optical characteristics. Controlled film thicknesses were achieved through precise manipulation of deposition parameters, enabling the analysis of oxidation-induced modifications. Atomic force microscopy (AFM) revealed that films with high structural integrity and surface uniformity are exhibiting roughness values (Rq) from 0.679 to 4.379 nm of corresponding thicknesses ranging from 4 to 85 nm. Scanning electron microscopy (SEM) validated the formation of Ni grains interspersed with NiO phases, facilitating SPR-like effects. UV-visible spectroscopy is demonstrating thickness-dependent spectral (plasmonic peak) shifts. Finite Difference Time Domain (FDTD) simulations corroborate the observed thickness-dependent optical absorbance and the resultant shifts in the absorbance-induced plasmonic peak position and bandgap. Increased NiO presence primarily drives the enhancement of electromagnetic (EM) field localization and the direct impact on power absorption efficiency, which are modulated by the tunability of the plasmonic peak position. Our work demonstrates that controlled fabrication conditions and optimal film thickness selection allow for accurate manipulation of the Ni oxidation process, significantly altering their optical properties. This enables the tailoring of these Ni films for applications in transparent conductive electrodes (TCEs), magneto-optic (MO) devices, spintronics, wear-resistant coatings, microelectronics, and photonics.

Enhanced absorption in thin-film silicon solar cells using a broadband plasmonic nanostructure

2025-06-18

Partha Mondal , Omar Alkhazragi , Hakan Bağcı | Optics Express

Strained Organic Thin‐Film Single Crystals for High‐Mobility and High‐Frequency Transistors

2025-06-17

Minoru Abe , Yu Yamashita , Taiki Sawada +4 more | Advanced Electronic Materials

Abstract Transistors fabricated from thin‐film single crystals of organic semiconductors (OSCs) have exhibited high mobility exceeding 10 cm 2 V −1 s −1 and show compatibility with low‐cost solution processing. … Abstract Transistors fabricated from thin‐film single crystals of organic semiconductors (OSCs) have exhibited high mobility exceeding 10 cm 2 V −1 s −1 and show compatibility with low‐cost solution processing. However, their carrier mobility is limited by the molecular vibrations in their soft lattices. This study establishes a practical method for applying compressive strain to single‐crystal OSCs to enhance mobility and transistor performance. In this method, a polymer film substrate is bent to mechanically stretch its surface. Organic single‐crystal transistors are then laminated onto the stretched surface of substrate. Releazing the stretch by recovering the flat surface of the substrate allowed the transistors to be compressed by up to 3%. This resulted in a 52% increase in mobility, reaching 26.4 cm 2 V −1 s −1 . X‐ray diffraction measurements confirmed lattice strain in the OSC single crystals. Moreover, carrier mobility and cutoff frequency increased in MHz‐operating short‐channel transistors, demonstrating applicability for high‐frequency devices. The mobility increase is maintained even three years after introducing the 1% compressive strain, possibly owing to the flexible, molecularly thin characteristics of OSC single crystals. The proposed strain management methods may provide new avenues to enhance the performance of high‐mobility and high‐frequency electronic devices based on OSC thin‐film single crystals.

Hydrogen passivation effects on polycrystalline germanium thin films

2025-06-17

Koki Nozawa , Kota Igura , Takuto Mizoguchi +4 more | NPG Asia Materials

Lamination Processes in Organic Photovoltaics for Indoor Applications

2025-06-16

Gulzada Beket | Linköping studies in science and technology. Dissertations

Edge Reinforcement of Ultrathin Crystal Silicon Enabling Stress Dispersion for Flexible Respiration Sensor

2025-06-16

Tianyi Zhao , Tianyu Lan , Zengzhe Xi +5 more | ACS Applied Electronic Materials

Filter‐Less Polychromatic Recognition in One Photosensitive Oscillator via Dual‐Perception Feature Decoupling

2025-06-16

Hailong Wang , Zhexin Li , Hao Xu +7 more | Small

Abstract Filter‐less polychromatic photodetectors play a critical role in miniaturized optoelectronic integration for spectral recognition, color imaging, and biometrics. However, parallel integration of several absorption‐selective semiconductors in one polychromatic pixel … Abstract Filter‐less polychromatic photodetectors play a critical role in miniaturized optoelectronic integration for spectral recognition, color imaging, and biometrics. However, parallel integration of several absorption‐selective semiconductors in one polychromatic pixel is indispensable, while polychromatic perception via a single semiconductor without optical components assistance seems difficult to achieve. Here, a filter‐less photosensitive ring oscillator (PSRO) based on a single amorphous semiconductor is demonstrated for polychromatic recognition. The distinguishable resolving ability for both wavelength and intensity in PSRO originates from decoupling oscillation frequency and relaxation character. The intrinsic localized defective states of amorphous IGZO contribute to relaxation character and fifth‐order oscillation architecture constructs frequency feature. The response oscillation frequency of PSRO up to ≈160 Hz and has recognizable detection in primary color waveband (450, 532, and 635 nm) range from 50 to 1500 µW cm −2 . An integration system based on PSRO with a response processing circuit has been demonstrated for application feasibility in polychromatic recognition. This work offers a kind of new methodology for polychromatic preceptors and advanced spectrometers.

Hard x-ray photoemission study of bulk single-crystalline InGaZnO4

2025-06-16

Goro Shibata , Yunosuke Takahashi , Mario Okawa +7 more | Applied Physics Letters

We performed hard x-ray photoemission spectroscopy experiments of bulk InGaZnO4 (IGZO-11) single crystals, which were recently synthesized via the optical floating zone method, in order to reveal the bulk intrinsic … We performed hard x-ray photoemission spectroscopy experiments of bulk InGaZnO4 (IGZO-11) single crystals, which were recently synthesized via the optical floating zone method, in order to reveal the bulk intrinsic electronic structure. We find that oxygen vacancies are preferentially located around In atoms in as-grown crystals, which are filled out by post-annealing in an oxygen atmosphere. We also find the presence of intrinsic hydroxy bonds, which persists even after oxygen annealing. The subgap states near the conduction-band minimum were clearly observed only in the as-grown crystals, while the subgap states near the valence-band maximum (VBM) were much weaker than those in the previous study even without oxygen annealing. The absence of the near-VBM subgap states in our single crystals suggests that in addition to oxygen vacancies, the loss of crystallinity is also relevant to the formation of the near-VBM subgap states.

Achieving Exceptional Stability in Self‐Aligned Coplanar Amorphous Oxide Thin‐Film Transistors through Hydrogen Scavenger Layer

2025-06-16

I. Sak Lee , Kyungmoon Kwak , Jae Won Na +1 more | Small Structures

Amorphous indium–gallium–zinc oxide (a‐IGZO) films, widely used as the active layer in thin‐film transistors (TFTs), require strict control of hydrogen levels for stability. Dehydrogenation processes are employed to reduce hydrogen … Amorphous indium–gallium–zinc oxide (a‐IGZO) films, widely used as the active layer in thin‐film transistors (TFTs), require strict control of hydrogen levels for stability. Dehydrogenation processes are employed to reduce hydrogen in the gate insulator and passivation (PAS) layers, preventing its diffusion into the channel. As devices scale down, even low concentrations of hydrogen can significantly impact performance, necessitating ultralow hydrogen levels in the effective channel. Here, a novel technique using the hydrogen scavenger layer (HSL) for blocking and capturing hydrogen from the PAS layer to the channel is reported. The insertion of the HSL not only blocks hydrogen molecules but also absorbs and retains them within the HSL. This induces remarkable enhancement in the qualities of the a‐IGZO films by minimizing the number of hydrogen‐related bonds and improving an exceptionally durable and reliable active layer. As a result, the a‐IGZO TFTs, compared to conventionally structured a‐IGZO TFTs, exhibit improved electrical performances in mobility from 9.87 to 12.91 cm 2 (V −1 s −1 ), active breakdown voltage from 79.2 to 141.8 V, transient current stress from 1.21% to 0.37%, and threshold voltage shift (under positive and negative bias temperature and illumination stress for 11 h at 50 °C) from −73 to −11 mV, and −9.86 to −2.31 V.

Vertical four-terminal polycrystalline-silicon thin-film transistors with high-k gate dielectric on glass substrates

2025-06-13

Kosei Suzuki , Akito Hara | Japanese Journal of Applied Physics

Abstract The channel length of vertical thin-film transistors (VTFTs) is determined by the thickness of the spacer layer, which corresponds to the step height. Therefore, VTFTs are expected to have … Abstract The channel length of vertical thin-film transistors (VTFTs) is determined by the thickness of the spacer layer, which corresponds to the step height. Therefore, VTFTs are expected to have structures that can achieve nanoscale channel lengths even on glass substrates. In addition, a four-terminal (4T) structure, in which two gates positioned opposite the channel can be operated independently, allows for threshold voltage control. The objective of this study was to improve the performance of the 4T poly-Si VTFT by introducing a high-k dielectric film as a top-gate insulating layer. In addition to the n-ch TFT, p-ch 4T poly-Si VTFTs were fabricated. Furthermore, the n-ch and p-ch 4T poly-Si VTFTs formed on different glass substrates were connected by wiring and a complementary metal-oxide semiconductor inverter with a supply voltage of 1.0 V and a transition threshold of 0.55 V was realized.

Oxide Ceramic Large‐scale Integration Device for Putting the Brakes on Global Boiling Accelerated by Artificial Intelligence Age Computers

2025-06-13

Shunpei Yamazaki , Tatsuya Onuki , Satoru Saito +7 more | International Journal of Ceramic Engineering & Science

ABSTRACT One factor that is considered to be a cause of global boiling, which is becoming a serious social problem, is the rapid progress and widespread use of artificial intelligence … ABSTRACT One factor that is considered to be a cause of global boiling, which is becoming a serious social problem, is the rapid progress and widespread use of artificial intelligence (AI). We focus on an oxide ceramic with an extremely low off‐state current ( I off ) of 1 zA/µm to 1 yA/µm and a very large on/off ratio of 17 digits, and we aim to achieve AI with an ultra‐low power consumption using the large‐scale integration of oxide semiconductors (OSs). Field effect transistors (FETs) that include crystal indium oxide (IO) as a channel material exhibit an off‐state current ( I off ) equivalent to that of the FETs that contain indium gallium zinc oxide (IGZO) and an on‐state current ( I on ) that is higher than that of the FETs that contain IGZO. Single crystal IO is shown to be a promising material for improving performance and reducing the variation in the characteristics of OS devices. This report introduces the latest trends in the use of oxide ceramics. We expect that the development of these technologies will achieve AI with ultra‐low power consumption in the future, which will be an important remediation against global boiling.

Smart capacitance sensing system on flexible substrate using oxide TFTs

2025-06-12

Suyash Shrivastava , Pydi Ganga Bahubalindruni , Nishtha Kansal +1 more | Analog Integrated Circuits and Signal Processing

Optimizing the PECVD Process for Stress-Controlled Silicon Nitride Films: Enhancement of Tensile Stress via UV Curing and Layered Deposition

2025-06-12

Jianping Ning , Chunjie Niu , Zhen Tang +3 more | Coatings

Silicon nitride (SiN) films deposited via plasma-enhanced chemical vapor deposition (PECVD) exhibit tunable tensile stress, which is critical for various microelectronic and optoelectronic applications. In this paper, the effects of … Silicon nitride (SiN) films deposited via plasma-enhanced chemical vapor deposition (PECVD) exhibit tunable tensile stress, which is critical for various microelectronic and optoelectronic applications. In this paper, the effects of silane (SiH4) flow rate during PECVD deposition, ultraviolet (UV) curing, and layered deposition on the tensile stress of SiN films are mainly investigated. The results reveal that increasing the SiH4 concentration raises hydrogen incorporation, which modifies internal stress dynamics. UV curing significantly increases tensile stress by breaking N-H and Si-H bonds, facilitating hydrogen desorption, and promoting Si-N-Si crosslinking. The optimal UV curing duration stabilizes tensile stress at approximately 1570 MPa, while excessive UV power alters hydrogen content dynamics, reducing stress. Additionally, layered deposition further amplifies stress enhancement, with films subjected to multiple deposition cycles exhibiting increased densification and crosslinking. The combined optimization of PECVD deposition parameters, UV curing, and layered deposition provides a robust strategy for tailoring SiN film stress, offering a versatile approach to engineering mechanical properties for advanced applications.

Improving IR drop effect and power noise using digital OLED power in AMOLED display

2025-06-11

Sanguk Lee , Byungmun Kang , Dae‐Eun Kim | Journal of Information Display

Enhancing Contact Properties in Organic Thin-Film Transistors by Incorporating Organic Solid-Solution Semiconductor Buffer Layers

2025-06-06

Beibei Yuan , Jidong Zhang , Haibo Wang | The Journal of Physical Chemistry Letters

The interface between organic semiconductors and metal electrodes remains a major challenge in organic thin-film transistors (OTFTs), which limits the transit frequency of OTFTs in logic circuits and leads to … The interface between organic semiconductors and metal electrodes remains a major challenge in organic thin-film transistors (OTFTs), which limits the transit frequency of OTFTs in logic circuits and leads to inaccurate assessment of charge transport. In this work, we propose a novel strategy to enhance interfacial contact by employing organic solid-solution films (SSFs) as buffer layers between electrodes and semiconductors. Finite organic solid-solution semiconductors, (P5)x(C8-BTBT)1-x, were successfully fabricated via coevaporation of P5 and C8-BTBT molecules. Substitutional solid solutions were formed for x < 0.5, while phase separation was observed for x ≥ 0.5. OTFTs incorporating SSFs as interfacial buffer layers effectively eliminate the nonlinear behavior of output characteristics, exhibiting a substantial reduction in contact resistance and achieving a high carrier mobility of up to 4.6 cm2/(V s). This improvement is attributed to interfacial energy level alignment and lattice matching, which significantly lower the injection barrier and reduce interfacial structural defects. Our results provide a promising approach for optimizing semiconductor/metal contacts to improve the overall performance of organic transistors.

Inkjet printing of amorphous indium aluminum oxide active layers for high-performance thin-film transistors

2025-06-03

Jiameng Kang , Kai Wang | Scientific Reports

Oxide semiconductors are regarded as a kind of promising active materials for thin-film transistors (TFTs) to drive organic light-emitting diodes (OLEDs) because of their advantages of high mobility, good electrical … Oxide semiconductors are regarded as a kind of promising active materials for thin-film transistors (TFTs) to drive organic light-emitting diodes (OLEDs) because of their advantages of high mobility, good electrical uniformity, and low cost. In this study, excellent metal oxide TFTs were successfully fabricated with a inkjet printer without any photolithography step. Indium aluminum oxide (IAO) active layers were fabricated at relative low post-annealing temperature and shown a n-type semiconductor behavior. The precursor solution with coalescing aid provided high-quality films, resulting in optimal device performance characteristics including a highest mobility of 59.7 cm2/V·s, steep subthreshold swing of 0.224 V/dec and high on/off ratio exceeding 9 × 106. These advantageous characteristics of the printed TFTs are very promising for future OLEDs, medical electronics, and large-scale integration of printed electronics.

ALD-Grown ZnO TFTs Patterned by High-Resolution Reverse-Offset Printing

2025-06-03

Fei Liu , Asko Sneck , Patrik Eskelinen +3 more | ACS Applied Materials & Interfaces

Zinc oxide (ZnO) is a benign and earth-abundant semiconductor material that has been applied in thin-film transistors (TFTs) for decades and can be used in biodegradable, transient, and biocompatible devices. … Zinc oxide (ZnO) is a benign and earth-abundant semiconductor material that has been applied in thin-film transistors (TFTs) for decades and can be used in biodegradable, transient, and biocompatible devices. Printing as an alternative fabrication method to conventional TFT manufacturing methods can deliver some benefits, such as simultaneous film deposition and patterning, good scalability, low cost, and material-saving features. However, the high annealing temperature needed for ink-to-metal oxide conversion and film densification, compounded by the poor patterning resolution of conventional printing methods, still limits the use of printing in the fabrication of flexible metal oxide TFTs. Atomic layer deposition (ALD) has recently emerged as a promising fabrication method for high-performance metal oxide TFTs that can offer more conformal film growth, precise film thickness, and higher film quality at low temperatures compared to sputtering, spin coating, or printing. Although ALD-based ZnO TFTs patterned with photolithography exhibit good electrical properties, they cannot be readily scaled to a high-throughput fabrication. Very little attention has been paid so far to the combination of low-temperature ALD growth with printing to obtain more scalable manufacturing of high-performance thin-film electronics. To overcome this challenge, we propose high-resolution reverse-offset printing (ROP) of a simple polymer resist to pattern an ALD-grown ZnO film at few μm resolution to fabricate TFTs. In this work, we report high-performance ZnO TFTs that are ALD-grown at a low temperature of 150 °C and ROP-patterned with promising stability and uniformity, a high field-effect mobility (μFE) of ∼16.6 cm2 (Vs)-1, an almost zero turn-on voltage (Von) of ∼-0.49 V, a high current on-off ratio (Ion/Ioff) of >108, a low operation voltage (Vop) of ≤5 V, and a negligible hysteresis (Vhyst) of ∼0.13 V. The combination of ALD and the ROP-patterning process could be developed further to fabricate fully flexible high-resolution metal oxide TFT-based circuits in the future.

Optimization of a-IGZO top gate thin film transistor for ammonia gas sensor

2025-06-02

Abhinandan Jain , P. Jain | Next Materials

Influence of Si Buffer Layer on the Crystal Quality of SiGe Films in Ge/Si/SiGe Heterostructures: A Molecular Dynamics Investigation

2025-06-01

Jianan Xie , Tao Lin , Cailin Wang | Surface Science

Fabrication of 4-inch Single-Crystalline InP Thin Film on Si Substrate by Ion-Cutting Technique with Wafer Bonding at Elevated Temperature

2025-06-01

Liang Tian , Hao Yu , Shujie Wang +7 more | Vacuum

Complementary inverter based on ZnO thin-film transistors

2025-06-01

Dunan Hu , Genyuan Yu , Rulin Yang +2 more | Journal of Semiconductors

Abstract Complementary inverter is the basic unit for logic circuits, but the inverters based on full oxide thin-film transistors (TFTs) are still very limited. The next challenge is to realize … Abstract Complementary inverter is the basic unit for logic circuits, but the inverters based on full oxide thin-film transistors (TFTs) are still very limited. The next challenge is to realize complementary inverters using homogeneous oxide semiconductors. Herein, we propose the design of complementary inverter based on full ZnO TFTs. Li−N dual-doped ZnO (ZnO:(Li,N)) acts as the p-type channel and Al-doped ZnO (ZnO:Al) serves as the n-type channel for fabrication of TFTs, and then the complementary inverter is produced with p- and n-type ZnO TFTs. The homogeneous ZnO-based complementary inverter has typical voltage transfer characteristics with the voltage gain of 13.34 at the supply voltage of 40 V. This work may open the door for the development of oxide complementary inverters for logic circuits.

Chain-Length-Dependent Nanostructure Evolution in InOx/PAM Composite Films: Interface Engineering for Electrical Performance Modulation

2025-06-01

Zhennan Zhu , Wei Lv , Hongcheng Wang +4 more | Surfaces and Interfaces

Industry 4.0-Enabled 3D Printing for Sustainable Antireflection Coversheets: Enhancing Photovoltaic Performance with Silicon Nitride-Modified Copolymers

2025-06-01

Mohamad Reda A. Refaai | Ceramics International

Continuous Grain Growth of High Band Gap InGaO on Crystalline In0.7Ga0.3O for 0.3 µm Channel Length Thin Film Transistors

2025-05-31

Myeonggi Jeong , Jinbaek Bae , Junyeong Kim +5 more | Advanced Materials Technologies

Abstract In‐based crystalline oxides have been of increasing interest for thin film transistors (TFTs) due to their high mobility and excellent stability. In 2 O 3 TFTs suffer from inferior … Abstract In‐based crystalline oxides have been of increasing interest for thin film transistors (TFTs) due to their high mobility and excellent stability. In 2 O 3 TFTs suffer from inferior stability so a stabilizer such as gallium (Ga) is necessary for stable crystalline(c‐) TFTs. However, excess dopants can disrupt the crystal structure of indium oxide, resulting in degraded TFT performance. In this study, continuous crystal growth of high Ga InGaO (IGO) on low Ga IGO by spray pyrolysis (SP) is investigated. IGO with higher Ga concentration grain grows by following the seed IGO. The In 0.5 Ga 0.5 O (In:Ga = 5:5) and In 0.4 Ga 0.6 O (In:Ga = 4:6) are grown on In 0.7 Ga 0.3 O for TFT applications, exhibiting the field‐effect mobility of 28.9 and 25.1 cm 2 V s −1 , respectively. Note that the field‐effect mobility of a single layer of In 0.7 Ga 0.3 O (In:Ga = 7:3) is 33.8 cm 2 V s −1 . The TFTs with 0.3 µm channel length are demonstrated with c‐In 0.4 Ga 0.6 O on c‐In 0.7 Ga 0.3 O layer. The c‐IGO with a high Ga concentration top layer has a lower carrier concentration and reduced oxygen vacancies, resulting in accumulation mode IGO TFT. The study proposes the application of short‐channel crystalline oxide TFTs for high‐resolution, active‐matrix organic and inorganic light‐emitting diode displays.