Deep levels in n-CdTe

Abstract

Deep-level transient spectroscopy (DLTS) was used to study electron traps in n-CdTe crystals. High-purity undoped and indium-doped samples were examined with Au Schottky barriers. Five levels were observed in CdTe:In, three of which are in good agreement with previously observed defect levels. The capture cross sections of these levels were measured. The energy levels relative to the conduction band were measured by isothermal DLTS. A single very deep level was observed in high-purity undoped CdTe. Modified CdTe surfaces were produced by brief (∼60 s) low-temperature (400 °C) annealing in air or argon. Schottky barriers made on these surfaces indicate a decrease in the near-surface carrier concentration. Changes in deep level concentrations were also observed. A very deep level (labeled IR5 in our study) (Ec =0.82 eV) is most changed by this process; annealing increases its concentration. It is suggested that IR5 is a native defect.

Electronic structure of the Cd vacancy in CdTe

“…Nevertheless, it seems clear that the mid-gap level that was frequently associated with VC; hasa different origin [1,2], so that no contradiction arises with our results. InZnSe Lee et al…”

Study of defect levels in CdTe using thermoelectric effect spectroscopy

“…To explain the high resistivity in CdTe, a compensation mechanism invoking deep-level defects has to be investigated. [10][11][12][13] The aim of this paper is to investigate and characterize the various defect levels in CdTe in as grown and postgrowth processed conditions. The samples were characterized using thermoelectric effect spectroscopy (TEES), thermally stimulated current (TSC) technique, and Hall-effect measurements.…”

A study on the mechanism of the hole density depletion in p-type cadmium telluride during heat treatment

“…Ar [4,6], Air [4] *Done in this work **Pulsed laser annealing the information from this study would be useful in achieving higher p-type doping of CdTe thin films. It is proposed by several authors [4][5][6] that for n-CdTe, this effect is caused by the creation and in-diffusion of Cd vacancies (Vcd) at the surface due to faster evaporation of Cd than Te from CdTe. As an acceptor species when ionized, V,.a may compensate donor impurities present in the material.…”

“…It is this similarity that interested us to study the mechanism responsible for the decrease of carrier density in annealed single crystals, because the gradient of the carrier density profiles that apper in p-CdTe films seems to be a result of the same reaction, and thus [1,2,7], N 2 111], Ar [11], Vacuum* As H2* n In H~, N. [5.81"*. Ar [4,6], Air [4] *Done in this work **Pulsed laser annealing the information from this study would be useful in achieving higher p-type doping of CdTe thin films. It is proposed by several authors [4][5][6] that for n-CdTe, this effect is caused by the creation and in-diffusion of Cd vacancies (Vcd) at the surface due to faster evaporation of Cd than Te from CdTe.…”