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

TL;DR

This study reports the growth of Ga2(SexTe1-x)3 single crystals with a zincblende structure, analyzes their defect characteristics using positron annihilation spectroscopy, and identifies vacancy-related defects and ordered vacancy planes.

Contribution

It introduces a modified Bridgman growth method for these semiconductors and provides detailed defect analysis using positron annihilation spectroscopy.

Findings

Large vacancy-related defects dominate the material

Ordered vacancy planes observed along [111] direction

Presence of vacancy clusters or voids confirmed

Abstract

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-resolution powder x-ray diffractometry confirms a zincblende cubic structure, with additional satellite peaks observed near the (111) Bragg line. This suggests the presence of ordered vacancy planes along the [111] direction that have been previously observed in Ga2Te3. Defect studies via positron annihilation spectroscopy show an average positron lifetime of ~400 ps in bulk as-grown specimens. Such a large lifetime suggests that the positron annihilation sites in these materials are dominated by defects. Moreover, analyzing the electron momenta via coincidence Doppler broadening measurements suggests a strong presence of large open-volume defects, likely to be vacancy clusters or voids.