Excitation Intensity Dependence of Photoluminescence in a-C:H and a-C Films

We present the novel results of excitation intensity dependent photoluminescence (PL) in a-C:H and a-C thin films. Sublinear and superlinear phenomena of PL have been observed for a-C:H films. There are two PL bands in a-C films under lower excitation intensity. These results are qualitatively explained in the light of band tail state saturation and the contribution of gap states.