Computer analysis of photoluminescence efficiency at InP surface with U-shaped surface state continuum

Abstract

Rigorous computer simulations of the dependence of the band-to-band photoluminescence quantum efficiency (YPL) were performed for n-type InP surfaces in a wide range of excitation light intensity, Φ (from 1018 to 1025cm−2s−1). A strong influence of the density of surface states (NSS) and their capture cross sections for electrons (σn) and holes (σp) on YPL–Φ dependencies was found. We reproduced very well the experimental dependence YPL–Φ, taken from the literature, for the chemically polished InP (100) surface, which exhibited strong increase of YPL. From the fitting of the experimental data we determined the surface state parameters, including the minimum density of U-shaped continuum (NSS0=1011eV−1cm−2), and capture cross sections (σn=10−14cm2 and σp=10−13cm2). The best fitting was carried out using a fully-computer procedure based on a novel Simple-Genetic-Algorithm (SGA) concept. In addition, the behaviour of the effective surface recombination velocity (Seff), and quasi-Fermi levels for electrons (EFn) and holes (EFp) was discussed.