Photoelectric and optical properties of layered compounds MgGaInS4 and Мg0,5Ga2InS5

Abstract

Single crystals of MgGaInS4and Мg0.5Ga2InS5with layered structure were obtained by a method of chemical vapor deposition with iodine as a transport agent. During the growth of single crystals, the temperature in the source zone was 880 °C, and in the crystallization zone 820 °C. A complete transfer of the charge was achieved within 12–14 days. The final product was a set of transparent lemon-yellow single-crystal plates 1–500 μm thick and up to 100 mm2in area. When exposed to air, the crystals do not show signs of interaction with oxygen or moisture and can be stored indefinitely long. The samples, like mica, could be easily split indicating their layered crystalline structure. X-ray studies showed that MgGaInS4crystallizes in a hexagonal lattice with parameters a = 3.8(1) Å and c = 30.6 Å; Mg0.5Ga2InS5crystallizes in a hexagonal lattice with parameters a = 3.8(1) Å and c = 12.2(1) Å. The c axis runs along the direction perpendicular to the plates. Surface barrier structures Pt–MgGaInS4–In were manufactured. Photoelectrical and optical properties of MgGaInS4and Мg0.5Ga2InS5and surface barrier structures on their basis were investigated. Surface-barrier structures had a rectification coefficient of 102–103and generated photo-e.m.f. when illuminated, the maximum value of which was 300 mV. The photoresponse time of these structures in the photovoltaic mode is τ ≈ 10−3 s.