Light induced defects in amorphous silicon-carbon alloys a-SiC:H

Silicon-carbon alloys were prepared using a UHV PECVD system by the mixture of CH4 + SiH4 with and without hydrogen dilution. The CH4 fraction in the plasma was varied between 40 and 95%. The energy gap of our samples varies between 1.8 and 2.5 eV. The effect of degradation induced by light exposure for several hours was studied using Photothermal Deflexion Spectroscopy (PDS). The experimental data are consistent with a bond breaking model, by conversion of tail weak bonds into dangling bonds. The data show more stability in the optoelectronic properties of diluted samples.