Thermal annealing in Te vapor atmosphere was adopted to improve the properties of indium-doped Cd_(1-x)Mn_xTe(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)×10~4 cm^(-3) to(2-4)×10~4 cm^(-3) and EPD from 10~5 cm^(-2) to 10~4 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)×10~8Ω·cm to(1.7-3.8)×10~9Ω·cm,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.
Readout electronics, especially digital electronics, for two-element CdZnTe （CZT） detectors in parallel are developed. The preliminary results show the detection efficiency of the two-element CZT detectors in parallel with analog electronics is as many as 1.8 and 2.1 times the single ones, and the energy resolution （FWHM） is limited by that of the single one by the means of analog electronics. However, the digital method for signal processing will be sufficiently better by contrast with an analog method especially in energy resolution. The energy resolution by the means of digital electronics can be improved by about 26.67%, compared to that only with analog electronics, while their detection efficiency is almost the same. The cause for this difference is also discussed.
