Synthesis and growth of GaSe single crystals

•One and two-temperature horizontal techniques were developed for synthesis of GaSe.•GaSe single crystals were obtained with yield 60% by Vertical Bridgman method.•The absorption coefficient over all transmission region of GaSe is ~0.1–0.12 cm−1.

One-temperature and two-temperature synthesis methods for GaSe, a nonlinear optical compound, were developed. X-ray diffraction showed that pure α-GaSe was synthesized. By Vertical Bridgman method using spontaneous nucleation the GaSe single crystals were grown with diameter 20–25 mm and length 40–45 mm and yield ~60%. The rocking curve for the studied GaSe sample was symmetric and its FWHM did not exceed 3′, which corresponds to the dislocation density at the level of 1012–1013 cm−2. SEM showed imperfections of surface of non-etched cleaved GaSe. According the obtained data the absorption coefficient at 1.06 μm and 2 μm is ~0.1 cm−1. At 9.3–10.9 μm for nonpolarized light the calculations give absorption coefficient ~0.1–0.12 cm−1.