Wide band gap amorphous silicon-based alloys

Abstract Wide band gap a-SiC:H and a-SiN:H films have been deposited by ultra high vacuum plasma enhanced chemical vapor deposition. For a-SiC:H films SiH 4 + CH 4 , SiH 4 + CH 4 + H 2 and SiH 4 + C 2 H 2 gas mixtures have been used, whereas for a-SiN:H films SiH 4 + NH 3 gas mixtures have been employed. The deposition conditions have been chosen for all the feedstocks to allow the growth of high electronic quality materials, in order to reach a complete understanding of analogies and differences in technological and physical characteristics of the two alloys, which is necessary for a more efficient use in electronic devices. Compositional, optical, structural, defective and electrical properties have been investigated for both a-SiC:H films, having optical gap in the range 1.9–3.25 eV, and a-SiN:H films, having optical gap in the range 1.9–5.2 eV. By Raman spectroscopy a lower structural disorder has been evidenced in a-SiC:H films compared to a-SiN:H ones and by electron spin resonance a lower spin density have been found in a-SiN:H films. The a-SiC:H and a-SiN:H films have similar electrical properties at the same band gap.