HYDROGEN DILUTION OF SILANE METHANE GAS-MIXTURES ON GROWTH AND STRUCTURE OF A-SI1-XCX-H ALLOYS

In this paper we have studied amorphous hydrogenated silicon-carbon, a -Si1-xCx:H, films grown by ultra high vacuum plasma enhanced chemical vapor deposition in undiluted and hydrogen diluted SiH4+CH4 gas mixtur es, having energy gap in the range 2.1-3.2 eV. The films have been cha racterized in optical properties by transmittance-reflectance spectros copy. The elemental composition has been determined by Rutherford back -scattering and elastic recoil detection analysis. The bonding structu re and the trends of bond concentration as a function of carbon conten t of the films have been studied by infrared spectroscopy. We have exp erimentally verified for the first time that the hydrogen dilution of the reactive gas mixtures acts on the microstructure of the a-Si1-xCx: H films by increasing the Si-C bond concentration, by decreasing the c arbon clusters and the CHn bonds, but unaffecting the hydrogenation of the silicon network.