Study of material uniformity in high-resistivity Cd_1−xZn_xTe and Cd_1−xMn_xTe crystals

In the last decade Cd_1−xMn_xTe (CMT) has been considered as a very promising material for room-temperature radiation detectors. Manganese has a better segregation compared to that of zinc in Cd_1−xZn_xTe (CZT), in addition MnTe has a wider bandgap than ZnTe enabling broader band “tunability” in the ternary alloy. In this work, we provided a general comparison of these materials grown in similar conditions, focusing, on material composition uniformity and electric properties under dark conditions. Results of material uniformity analyses clearly confirm better homogeneity of CMT crystals, both laterally and in-depth. In addition to material studies, the current–voltage (I–V) characteristics of both In/CZT/In and In/CMT/In metal–semiconductor–metal (MSM) structures were characterized. The results revealed significantly lower variations in contact-to-contact currents in CMT compared to that in CZT (10% and 25% variance, respectively). The temperature behavior of I–V in In/CZT/In and In/CMT/In devices was investigated with calculation of dark current activation energy. The activation energies of dark current mechanisms in CMT were found to be similar at both polarities, whereas there was a 0.2 eV polarity-related difference in CZT based structures.