Effect of Cr/In-doping on the crystalline quality of bulk ZnTe crystals grown from Te solution by temperature gradient solution growth (TGSG) method

The properties of undoped, Cr-doped, and In-doped bulk ZnTe crystals grown by the TGSG method were compared. Cr/In-doping leads to a slight red-shift of the absorption edge. Cr-doping also creates two characteristic absorption bands, centered at about 1750 nm and beneath the fundamental absorption edge. However, the fundamental reflectance spectra are not sensitive to the dopants. The resistivity of undoped, Cr-doped, and In-doped ZnTe is about 10² Ω•cm, 10³ Ω•cm, and 10⁸ Ω•cm, respectively. Only In-doped ZnTe has an IR transmittance higher than 60% in the range of 500 to 4000 cm^-1. However, the IR transmittance of Cr-doped ZnTe is very low and decreases greatly as the wavenumber increases, which is mainly attributed to the scattering effects caused by some defects generated by Cr-doping.