The effect of dopant concentration and annealing treatments on N-type Iodine doped CdTe

We report properties of highly conducting n-type cadmium telluride single crystals doped with iodine (CdTe:I). These crystals were grown with dopant concentrations in the range of 1017 cm-3 to 1019 cm-3 by Modified Vertical Bridgman (MVB) melt growth. Post-growth dopant activation, including Cd annealing, Te annealing, and rapid thermal annealing (RTA), was applied to improve free carrier density. The structural, optical, and electrical properties were analyzed by Glow Discharge Mass Spectroscopy (GDMS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Photoluminescence Spectroscopy (PL), optical absorption, Hall measurements, Capacitance-Voltage (CV) measurements, and time-resolved photo-luminescence (TRPL). The results indicate that Cd annealing is the most effective activation method to get 100 % donor activation (n approximate to 2 x1018 cm-3), which is close to the room temperature solubility limit of iodine. This leads to the lowest resistivity and the highest mobility. Moreover, this data suggests a potential role of Cd vacancy-related defects on electrical self-compensation.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

We report the properties of highly conducting n-type cadmium telluride single crystals doped with iodine (CdTe: I). The crystals were grown using the Modified Vertical Bridgman (MVB) melt growth method with dopant concentrations ranging from 1017 cm-3 to 1019 cm-3. Post-growth dopant activation techniques, including Cd annealing, Te annealing, and rapid thermal annealing (RTA), were applied to improve the free carrier density. The structural, optical, and electrical properties were analyzed using various techniques. The results show that Cd annealing is the most effective activation method, resulting in the highest donor activation, lowest resistivity, and highest mobility. The study also suggests the potential role of Cd vacancy-related defects in electrical self-compensation.