Results are presented on the electrical and optical‐absorption spectra (hv < Eg) of p‐ZnGeP crystals before and after electron irradiation (2 MeV, 300 K), and post‐irradiated annealing (300 to 870 K). The defect or impurity level at about (Ev + 0.6) eV (N ≊ 5 × 1017 cm−3) which is responsible for the optical‐absorption in the spectral range 0.6 to 1.3 eV is found in initial samples. The enlightment of the samples in the spectral range 0.6 to 1.3 eV is found after electron irradiation and this is connected with the Fermi level moving up to ≈︁ Eg/2 during irradiation. Isochronal annealing experiments indicate three regions of annealing at temperature 410 to 450 K (Ea ≊ = 1.1 eV), 480 to 550 K (Ea ≊ 1.4 eV) and 550 to 770 K. It is supposed that the electrical and optical property changes of ZnGeP2 upon electron bombardment are connected with formation of simple point defects [Vzn], [VGe], and [VP].

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.

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