Charge-carrier lifetimes in high-resistance GaAs doped by chromium diffusion

Abstract

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 (τ n ) and hole (τ p ) lifetimes are estimated for high and low excitation levels. It is found that τ p > τ 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.

Photoelectrical characteristics of as-grown highresistance GaAs single crystals

“…Earlier, we estimated the charge-carrier lifetimes in the material of the first type [3]. We obtained the following values of lifetimes: τ n ≈ 7·10 -8 s and τ p ≈ 2.5·10 -7 s. These values are much higher than the corresponding values even for relatively pure GaAs:EL2 and hundred times as high as those in GaAs:Cr.…”

“…It is of physical and practical interest to find the reasons for the differences between the properties of diffusion and as-grown high-resistance GaAs. The results of studying the properties of the diffusion high-resistance material are reported in [3]. In this work, the electrophysical properties, photoconductivity, and photo-Hall effect are studied and the stationary charge-carrier lifetimes are calculated for as-grown HR GaAs.…”

Optical Pump–Terahertz Probe Study of HR GaAs:Cr and SI GaAs:EL2 Structures with Long Charge Carrier Lifetimes

“…For some devices-for example, photoconductive dipole antennas [1]-a short lifetime is required, and it can reach 200-500 fs in some gallium arsenide structures [2,3]. Contrary to this, for gallium arsenide X-ray detectors, structures with a long charge carrier lifetime, which can reach hundreds of nanoseconds, are necessary [4][5][6]. Thus, semiconductor material modification methods are required in order to change the charge carrier lifetime.…”

Фотолюминесценция с временным разрешением в гетероструктурах с квантовыми ямами InGaAs:Cr/GaAs

“…Наконец, легирование полупроводников A III B V атомами переходных элементов можно считать " традиционным" приемом для управления рекомбинационными характеристиками структур, а именно соотношением времен излучательной и безызлучательной рекомбинации [5,6].…”