Density of states determination from steady-state photocarrier grating measurements

Abstract

We present a method to obtain the density of states (DOS) of photoconductive insulators based on steady-state photocarrier grating (SSPG) measurements. A simple expression—relating the DOS at the electron quasi-Fermi level to measurable quantities—is deduced by performing suitable approximations from the analytical solution of the generalized equations that describe the SSPG experiment. The validity of the approximations and the applicability of the final expression are verified from numerical simulations of the process. The usefulness of the method is demonstrated by performing measurements on a standard hydrogenated amorphous silicon sample.