Compositional and structural analysis of hydrogenated amorphous silicon—nitrogen alloys prepared by plasma-enhanced chemical vapour deposition

Amorphous hydrogenated silicon-nitrogen alloys (a-Si1−x N x : H), having energy gaps in the range 2·0–5·2 eV, have been deposited in ultra-high vacuum by 13·56Mhz plasma-enhanced chemical vapour deposition from SiH4+NH3 gas mixtures with Nha percentages in the range 6·2–97·3%. The compositions of the films were obtained by Rutherford back-scattering spectroscopy and elastic recoil detection analysis and the structure and the bonding configurations studied by infrared and Raman spectroscopies. Films having a nitrogen content x in the range 0·07–0·63 and a hydrogen content as high as 38at.% have been obtained. For x < 0·5, the hydrogen is mainly bonded to silicon and nitrogen is prevalently incorporated in the Nsis configuration. For x > 0·5, NH n bonds become predominant, which allows the growth of stoichiometric and over-stoichiometric films.