Characterization of Cr-doped ZnTe crystals grown by temperature gradient solution growth (TGSG)

Cr-doped ZnTe ingot was grown by temperature gradient solution growth (TGSG), using CrTe and Te as dopant source and solvent, respectively. Single crystals in the head of the ingot have larger size of more than 10 mm× 10 mm and less Te inclusions. The size, shape and distribution of Te inclusions well reflect the thermal field distribution of the ingot. Radial asymmetric thermal field of the ingot leads to radial asymmetric distribution of Te inclusions. The thermal migration of Te inclusions under thermal gradient results in their merging, enlargement and enlongation. Defects such as cracks and voids can be introduced into ZnTe matrix by Te inclusions. Some excess amount of CrTe is rejected by the advancing interface, which indicates that the present growth method has self purification effect. The resistivity of Cr-doped ZnTe ( about 1000 Ω·cm ) is slightly higher than that of ZnTe (about 300 Ω·cm). Cr-doped ZnTe exhibits an absorption centered at about 1750 nm, which means Cr²⁺ ions are successfully incorporated into ZnTe. IR transmittance of Cr-doped ZnTe is lower than that of ZnTe, which can be attributed to defects caused by Cr doping.