Effect of Oxygen-Related Defects on Electrical Properties of Cd0.9Zn0.1Te Semiconductor

Abstract

The impurity from raw material in the as-grown crystal is one of the most important factors that hamper the advancement of Cd0.9Zn0.1Te (CZT) detectors. However, the influence of impurity oxygen is rarely reported. In this study, the first principle calculation is carried out to give a prediction about transition levels of oxygen-related defects. Glow discharge mass spectrometry (GDMS) is used to determine the concentration of all the elements. The quantitative analysis of oxygen-related defects is carried out by deep-level transient spectrum (I-DLTS), which can break through the limitations of traditional C-DLTS testing in the field of high-resistance materials. The peaks observed at about 50 and 100 K are related to the level of (VCd–O $_{\mathrm {Te}})^{0/-}$ and (VCd–O $_{\mathrm {Te}})^{-/2-}$ defect pair, with energy about $E_{\mathrm {v}} +0.079$ eV and $E_{\mathrm {V}} +0.173$ eV, trap cross section about $3.02\times 10^{-19}$ and $1.01\times 10^{-19}$ cm2, respectively. The effect of oxygen on ( $\mu \tau)_{e}$ of the CZT semiconductors is evaluated through Alpha particle spectrum response testing by fitting the charge collection efficiency with applied bias voltages. The ( $\mu \tau)_{e}$ is about $5.21\times 10^{-4}$ cm2/V in CZT with more oxygen and $2.33\times 10^{-3}$ cm2/V with less oxygen. The mobility is obtained from the results of the time of flight (TOF) testing through the laser-beam-induced current (LBIC) technique, to be around 1000 cm2/V $\cdot $ s1 for both samples, and the lifetime to be 494 and 2407 ns, respectively. It can be concluded that oxygen-related defects can terribly affect the electron transport properties.