Photoluminescence lifetime distribution of a-Si:H and a-Ge:H expanded to nanosecond region using wide-band frequency-resolved spectroscopy

We present the first survey on quadrature frequency-resolved spectroscopy (QFRS) spectra in the nanosecond (ns) region of photoluminescence (PL) of a-Si:H and a-Ge:H. Our QFRS study reveals that there is no evidence of a peak or shoulder for the ns PL lifetime component, and thus the PL lifetime distribution has basically a double-peak structure with two components of mus and ms lifetimes in both materials. The ps component in the lifetime distribution is enhanced at higher PL photon energy, which favors the exciton model. Generation rate (G) dependence of QFRS spectra shows a common feature, for both a-Si:H and a-Ge:H. where excitonic emission shifts to non-geminate radiative recombination as G increases. (C) 2002 Elsevier Science B.V. All rights reserved.