Photoluminescence band centered near 0.9 eV in microcrystalline silicon films

In this work we investigated the low-energy photoluminescence (PL) band with a peak between 0.8 eV and 1.0 eV for microcrystalline silicon (μc-Si:H) films. The characteristics of the low energy PL were examined for μc-Si:H films grown by plasma-enhanced chemical vapor deposition (PECVD) under various growth conditions. At least four subbands were observed, the peaks of which were located near 0.80 eV, 0.87 eV, 0.92 eV, and 0.97 eV, respectively. The low-energy PL band is suggested to basically arise from a superposition of these subbands, whose intensities strongly depend on the deposition conditions. The results suggest that the subband centered at 0.92 eV originates from defect-related radiative recombination in the amorphous phase rather than radiative band tail-to-tail transitions.