BONDING STRUCTURE AND DEFECTS IN WIDE-BAND GAP A-SI1-XCX-H FILMS DEPOSITED IN H-2 DILUTED SIH4-MIXTURES(CH4 GAS)

Amorphous silicon-carbon thin films have been deposited by a newly des igned ultra-high vacuum plasma enhanced chemical vapour deposition sys tem starting from SiH4 + CH4 gas mixtures at different Y(CH4)=CH4/(SiH 4 + CH4) ratios with deposition conditions optimized to grow high-qual ity material, having energy gaps in the range 1.9-3.5 eV. The effect o f the addition of hydrogen to the plasma with Z(H-2)=H-2/(SiH4 + CH4 H-2) ranging from 0 to 0.95 has been investigated. A detailed analysi s of elemental composition, obtained by Rutherford backscattering and elastic recoil detection analysis, and of structural properties, obtai ned by infrared and Raman spectroscopies, has been carried out. The re sults have been correlated to the plasma conditions, the disorder and the optoelectronic properties of the a-Si1-xCx:H films.