Photoconductivity investigation of the electron dynamics in GaAs grown at low temperature

Abstract

We present detailed measurements of photoconductivity as functions of illumination power and temperature on metal–semiconductor–metal photodetectors made of low-temperature GaAs grown at different temperatures (225–350 °C). The extracted carrier lifetimes show the expected dependence as a function of growth temperature. Additionally, our experiments show an order-of-magnitude variation of the extracted lifetimes as functions of measurement temperature and illumination intensity. We propose a simple model based on the one-center-Shockley Read-recombination equation which gives good qualitative agreement over the whole range of temperature (20–120 °C) and illumination power (2×10−4 to 20 W/cm2). We show that the recombination properties are determined by the exact position of the electronic quasi-Fermi level in the partially filled midgap donor band, which is strongly influenced by the acceptor concentration.