Effects of annealing on the optical and electrical properties of CdZnTe crystals

The CdZnTe crystals were annealed in Cd/Zn vapor and Te vapor under different temperature and time to investigate the effects of the annealing on the optical and electrical properties of CdZnTe single crystals. The results indicate that after Cd/Zn vapor annealing for 180 h, the mean area density of Te inclusions (> 5 μm) has reduced by one order while the resistivity declined from 10¹⁰ Ω·cm to ~10⁷ Ω·cm. It has been found that the shape of infrared trans-mittance curve depended on the temperature of Cd/Zn source which may be related to the concentration of Cd interstitials atoms rather than the concentration of free carriers and the configuration of Te inclusions or precipitates. In order to determine the factor that affects the infrared transmittance curve, Te vapor annealing has been carried out. After Te vapor annealing, the resistivity has recovered to 10¹⁰ Ω·cm. The shape of the infrared transmittance δ varies approximate linearly with the logarithm of the crystal resistivity under Te vapor annealing, which can also be attributed to the concentration variation of the Cd interstitial atoms.