Photoluminescent, wide-bandgap a-SiC : H alloy films deposited by Cat-CVD using acetylene

Hydrogenated amorphous silicon/carbon films (a-Si-C:H) are deposited from a silane and acetylene gas mixture by the catalytic chemical vapour depositi on (Cat-CVD) technique. It is observed that under certain conditions of tot al gas pressure and filament temperature (T-F), the optical bandgap varies non-linearly with the acetylene to silane (C2H2/SiH4) ratio, having a maxim um value of 3.6 eV for a C2H2/SiH4 ratio greater than or equal to0.8. Howev er, the deposition rate drastically reduces with an increase in acetylene f raction. FTIR spectra indicate that the total hydrogen content is lower com pared to samples deposited by PECVD using similar gas mixtures, with hydrog en being preferentially attached to carbon rather than silicon atoms. The p hotoluminescence (PL) spectra of these films show PL in the visible spectra l region at room temperature. The films with larger bandgap (>2.5 eV) exhib it PL at room temperature, with the emission having peak energy in the rang e 2.0-2.3 eV. (C) 2001 Elsevier Science B.V. All rights reserved.