  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.
