Improved growth and characterization of AgGa1−xInxSe2 crystals

Good quality AgGa1−xInxSe2 (x=0.1–0.3) single crystals with 20 mm diameter and 60 mm length have been grown by an improved Bridgman method, i.e. descending ampoule with rotation and the real-time temperature compensation technique. The melt temperature oscillation method (MTOM) was used to synthesize high-purity single-phase AgGa1−xInxSe2 polycrystal that is free of voids. The crystallization process was carried out in the two-layer quartz ampoule with a seed pocket. The temperature gradient at the growth interface in the furnace was normally 20 °C cm−1 in the open bore, while it was 15 °C cm−1 with the ampoule in the furnace. The quality of the as-grown crystal was characterized by using X-ray diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), infrared (IR) spectrophotometer, etc. It was found that there is a {1 1 2} cleavage face in the as-grown crystal and the homogeneous growth steps on the {1 1 2} face were observed. The four-order diffraction peaks of the {1 0 1} faces were evident. The transmittance of the crystal sample of 2 mm thickness is up to 65% in the region of 700–6500 cm−1. The results demonstrated that the improved new growth method of AgGa1−xInxSe2 single crystals is promising and the quality of the grown crystals is good, and after annealing, the crystals can be used for IR nonlinear optical devices.