Single Crystal Growth of Ga2(SexTe1-x)3 Semiconductors and Defect Studies via Positron Annihilation Spectroscopy

摘要

Small single crystals of Ga2(SexTe1-x)3 semiconductors, for x = 0.1, 0.2,0.3, were obtained via modified Bridgman growth techniques. High-resolutionpowder x-ray diffractometry confirms a zincblende cubic structure, withadditional satellite peaks observed near the (111) Bragg line. This suggeststhe presence of ordered vacancy planes along the [111] direction that have beenpreviously observed in Ga2Te3. Defect studies via positron annihilationspectroscopy show an average positron lifetime of ~400 ps in bulk as-grownspecimens. Such a large lifetime suggests that the positron annihilation sitesin these materials are dominated by defects. Moreover, analyzing the electronmomenta via coincidence Doppler broadening measurements suggests a strongpresence of large open-volume defects, likely to be vacancy clusters or voids.