CHARGE-CARRIER LIFETIMES IN HIGH-RESISTANCE GaAs DOPED BY CHROMIUM DIFFUSION

Application of high-resistance GaAs for the formation of ionizing radiation detectors calls for investigation of physical properties of this material. Studying the photoelectrical properties makes it possible to establish the recombination mechanisms of charge carriers and peculiarities of their transport in the electric fields as well as to evaluate the charge-carrier lifetimes. In this work, the results of studying the photoconductivity and Hall photoeffect are discussed for high-resistance GaAs doped by chromium diffusion. A typical lux-ampere characteristic is shown to consist of two parts: a superlinear part and a sublinear one. Changes in the Hall mobility under illumination are studied. A number of simplifications are made and the electron (tau(n)) and hole (tau(p)) lifetimes are estimated for high and low excitation levels. It is found that tau(p) > tau(n). It is shown that the photoelectrical properties of high-resistance GaAs: Cr can be explained using the model of curved bands. It is assumed that the potential barriers are transformed under photoexcitation.