Multimodal characterization of Te inclusions in Cd1-xZnxTe and Cd1-xZnxTe1-ySey for gamma and x-ray detector applications

CdZnTe (CZT) and CdZnTeSe (CZTS) semiconductors have significant potential for room-temperature gamma-ray and x-ray detector applications. However, the presence of tellurium (Te) inclusions, formed during growth and post-growth processes, introduces trapping centers, which is detrimental to the detector performance. Several efforts, such as compound doping, modification of growth parameters, thermal annealing, etc. have been implemented to overcome it, but still the active point and extended defects remain a critical challenge. In the present study, we employed multimodal imaging and spectroscopic analysis integrating atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), confocal Raman microscopy, and infrared scattering-scanning near-field optical microscopy (IRS-SNOM) to characterize Te inclusions in CZT and CZTS crystals at micro- and nanoscale levels. For the first time, IR optical response mapping is utilized to precisely locate and analyze the geometric distribution and electronic properties of Te-inclusions. The findings offer crucial insights into how secondary phases hinder carrier transport in radiation detector materials.