Wide Optical-Gap, Photoconductive a-Si_xN_1-x:H

Abstract

The electrical and optical properties of a-Si x N 1- x :H prepared by the glow discharge of a SiH 4 -NH 3 -H 2 gas mixture have been systematically investigated as a function of the ammonia-to-silane molar fraction. The optical bandgap increases smoothly from 1.75 eV to 5.5 eV as the molar fraction increases. A normalized photoconductivity ηµτ larger than 10 -6 cm 2 V -1 is easily obtained in the ammonia fraction range 3.3×10 -3 to 0.60, and it has a maximum (ηµτ≧4.8 ×10 -5 cm 2 V 1 ) around a fraction of 0.1.