Te vapor annealing of indium-doped CdMnTe crystals

Thermal annealing in Te vapor atmosphere was adopted to improve the properties of indium-doped Cd1−xMnxTe (x = 0.2, CdMnTe) wafers grown by the vertical Bridgman method. The wafers before and after annealing were characterized by measuring the Te inclusions, etch pit density (EPD), Mn composition, resistivity, and impurity. IR transmission microscopy and EPD measurements revealed that the densities of Te inclusions reduced from (5–9) × 104 cm−3 to (2–4) × 104 cm−3 and EPD from 105 cm−2 to 104 cm−2 after annealing. NIR transmission spectroscopy showed that the Mn composition increased by 0.002–0.005 mole fractions during the annealing. The resistivity of the wafers improved from (2.0–4.5) × 108 Ωcm to (1.7–3.8) × 109 Ωcm, which suggested that the deep-level donor of Te antisites was successfully introduced after annealing. Inductively coupled plasma-mass spectrometry (ICP-MS) revealed that the concentrations of impurities in the wafer decreased, which indicated the purifying effects of Te vapor annealing on the wafers. All the results demonstrate that the Te vapor annealing of the indium-doped CdMnTe crystal has positive effects on the crystallinity, resistivity and purity of CdMnTe wafers.