Lifetime of defect luminescence in hydrogenated amorphous silicon

摘要

We have investigated the dependence of lifetime distribution of photbluminescence (PL) in a-Si:H films on the defect density. In order to analyse the lifetime distribution quantitatively, we estimated characteristic lifetime from the in-phase signal obtained by frequency resolved spectroscopy (FRS). The increase of lifetime of PL due to contribution of emission from triplet excitons trapped at defects is seen at 0.95-1.13 eV. The characteristic lifetime of emission from electron-hole pairs is discussed by considering the probability of tunnelling to non-radiative recombination centres and radii of wave functions of gap states and tail states.