Photon-recycling and optically driven plasma-expansion techniques applied to lifetime experiments on molecular-beam-epitaxy ZnSe

Abstract

Transient-grating techniques are used to investigate the picosecond dynamics of photoexcited carriers in a range of n- and p-doped ZnSe thin-film layers grown by molecular-beam epitaxy. Two-photon absorption is employed experimentally to generate known excitation levels, comparable with those under laser action in II–VI diode structures. The analysis of the measured grating decays, incorporating photon recycling, reveals carrier lifetimes of the order of 300 ps and radiative recombination coefficients of the order of 10−8 cm3 s−1. The influence of photon-assisted plasma expansion at excitation levels above the threshold for stimulated emission is modeled and quantified.