Characterizations of ZnSe single crystals grown by physical vapor transport

ZnSe bulk crystals were grown by self-seeded physical vapor transport technique in horizontal and vertical configurations. The impurities and defects in the grown crystals were studied by glow discharge mass spectroscopy (GDMS) and low-temperature photoluminescence (PL) measurements. The PL results on the starting material and the grown crystals are consistent with the low impurity levels measured by GDMS. The crystalline quality of the grown crystals was examined by synchrotron white beam X-ray topography (SWBXT) and high-resolution triple X-ray diffraction (HRTXD). The SWBXT shows that, aside from twins, the overall crystalline quality of the vapor-grown ZnSe crystals, especially in the contactless grown region, was quite high. The HRTXD results are in line with the SWBXT findings. The comparison between the HRTXD on a chemical-mechanically polished and a cleaved surface seems to indicate that polishing damage can obscure the true microstructure in the as-grown ZnSe crystals.