Preparation and Some Optical Properties of Semiconducting Compounds ZnGeP<SUB>2</SUB> and CdSiP<SUB>2</SUB>

Abstract

Crystal growthes of the II-IV-V2 group semiconducting compounds ZnGeP2 and CdSiP2 were carried out by a direct melting method and a solution growth method, respectively. The optical properties were chiefly investigated for the obtained crystals.By a solution growth method with the Sn bath, under the condition of 22 mol%CdSiP2 concentration and 2°C/hr cooling rate, the CdSiP2 single crystals with approximate dimensions of 6×2×1 mm3 were obtained. The resistivities at room temperature for the compounds are the large values of the order of 106 Ω-cm (ZnGeP2) or 103 Ω-cm (CdSiP2). According to the results of measurements of the absorption coefficients in the range from room temperature to nearly liquid nitrogen temperature, the fundamental absorptions for these compounds are considered to be of indirect transitions. The energy gaps at room temperature are 1.81 eV (ZnGeP2) and 2.21 eV (CdSiP2), and they show linear temperature dependences with gradients −5.3×10−4 and −8.4×10−4 eV/deg, respectively.