Atomistic Origin of Urbach Tails in Amorphous Silicon
Atomistic Origin of Urbach Tails in Amorphous Silicon
Exponential band edges have been observed in a variety of materials, both crystalline and amorphous. In this Letter, we infer the structural origins of these tails in amorphous and defective crystalline Si by direct calculation with current ab initio methods. We find that exponential tails appear in relaxed models of …