Characteristics of the low energy photoluminescence in mu c-Si films

The temperature and excitation-intensity dependence of the similar to 0.9 e V photoluminescence (PL) band has been studied in several microcrystalline silicon (mu c-Si) films with varied crystallinity. When the measurement tem perature is increased from 15 to 180 K, the PL peak energy redshifts from 1 .0 to 0.83 eV. The PL quenching of the intensity follows a model of carrier thermalization in an exponential band tail with a width of similar to 20 m eV. The total PL intensity (I-PL) as a function of excitation intensity (I- ex) obeys a power law of I(PL)proportional to I-ex(gamma), where gamma appr oximate to 0.65 or 1 for high or low excitation intensity, respectively. Th e experimental results suggest that the similar to 0.9 eV PL band originate s from radiative tail-to-tail transitions in the grain-boundary region in m u c-Si. (C) 2000 American Institute of Physics. [S0021-8979(00)06919-X].