Optoelectronic effects in p-CdGeAs₂ single crystals and structures based on them

Abstract

Spectra of inelastic light scattering by optical phonons in p-CdGeAs₂ single crystals were obtained for the first time. The observed clear polarization dependence and the absence of any appreciable dependence of the intensity and frequency of the observed lines when the sample is swept in ≈300 µm steps indicates these CdGeAs₂ single crystals grown by directional crystallization from a near-stoichiometric flux, are of high quality and homogeneous. The type of symmetry of the observed phonon lines is interpreted and it is shown that the force constants in CdGeAs₂ and CdSnP₂ crystals differ slightly. Temperature dependences of the electrical conductivity and the Hall constant were studied in oriented homogeneous p-CdGeAs₂ single crystals. It was established that the conductivity of these crystals is determined by the deep acceptor level E _A=0.175 eV and has the degree of compensation 0.5–0.6. The temperature dependence of the Hall mobility reflects the competition between impurity and lattice mechanisms of hole scattering. The photosensitivity of In/CdGeAs₂ surface barrier structures reaches 20 µA/W at T=300 K and remains at this level within the fundamental absorption of CdGeAs₂. It is concluded that these structures may be used as wide-band photoconverters for natural light and as selective photoanalyzers for linearly polarized radiation.