Structure and microstructure of GaTe crystals grown by High-Pressure vertical zone melting

GaTe crystals of 20 mm in diameter and up to 70 mm in length have been grown from melt using the high-pressure vertical zone melting (HPVZM) method. Real defect structure has been evaluated by XRD, SEM, EPMA, optical microscopy, microhardness and transparency measurements. The phase transformation of hexagonal GaTe single crystal to monoclinic form by grinding has been detected. Such local defects as dendrites and dendrite clusters have been found at cleaved surface (0001), basal dislocations with density of 2×105 cm−2 have been detected by the etch-pit technique.

► High-pressure zone melting was developed for crystal growth of GaTe single crystals. ► Grown crystals have hexagonal structure, which transforms into monoclinic upon grinding. ► Formation and decomposition of dendrites associated with unstable growth have been studied. ► Microhardness of the grown crystals is 350 MPa, they are transparent in IR and visible ranges. ► Energy gap measured by absorption edge is Eg=1.5 eV.