On The Validities And Limitations Of Transient Photo-Decay Techniques For Identifying The Energy Distribution And Related Properties Of Localized States In Disordered Semiconductors

A computer simulation technique is employed to calculate the transient photo-decay characteristics for a disordered semiconductor featuring an exponential tail of localized states plus a narrow Gaussian feature of adjustable height. The resulting data are subjected to analysis via the “pretransit” (1/I(t).t), “post-transit” (1/I(t).t) and “Fourier transform” procedures. It is shown that all three options can detect the presence of the Gaussian component. However, even when the peak height of this becomes comparable to or less than that of the local exponential background, the pre-transit procedure consistently miscalculates its energy. In contrast, the post-transit and Fourier transform procedures correctly identify this energy, and also provide improved resolution of the energy distribution and other properties of the localized states.