COMPOSITIONAL AND STRUCTURAL-ANALYSIS OF HYDROGENATED AMORPHOUS SILICON-NITROGEN ALLOYS PREPARED BY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

Amorphous hydrogenated silicon-nitrogen alloys (a-Si1-xNx:H), having e nergy gaps in the range 2.0-5.2 eV, have been deposited in ultra-high vacuum by 13.56 MHz plasma-enhanced chemical vapour deposition from Si H4+NH3 gas mixtures with NH3 percentages in the range 6.2-97.3%. The c ompositions of the films were obtained by Rutherford back-scattering s pectroscopy and elastic recoil detection analysis and the structure an d the bonding configurations studied by infrared and Raman spectroscop ies. Films having a nitrogen content x in the range 0.07-0.63 and a hy drogen content as high as 38 at.% have been obtained. For x < 0.5, the hydrogen is mainly bonded to silicon and nitrogen is prevalently inco rporated in the NSi3 configuration. For x > 0.5, NHn bonds become pred ominant, which allows the growth of stoichiometric and overstoichiomet ric films.