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The wetting and sticking phenomena are the principal factors that lead to dislocation, parasitic grain nucleation, cracking, and other issues during crucible-based crystal growth of Cd-based crystals (CdTe/Cd1−xZnxTe). The trace amount of moisture in raw materials is an important factor influencing the sticking process, but this has not been sufficiently studied. Here, we investigate the chemical reactions between trace moisture and raw Cd materials by introducing H2O intentionally. The X-ray photoelectron spectra of the sticky surface indicate that residual moisture can react with raw Cd and generate more CdO compared with the untreated Cd. The reactive gas atmosphere process (RAP) method with a self-designed crucible was modified for the removal of moisture and reaction products. The waste products of the RAP method were successfully separated and determined to be CdCl2, CdCO3, CdO, and SiO2. The whole chemical process of oxidation and the RAP method was proposed accordingly. The purified Cd showed a spherical shape derived from the surface tension and de-wetting with the bare quartz crucible. These studies provide a comprehensive description of the moisture-driven oxidation behavior of Cd responsible for the sticking problem of the Cd/SiO2 system, which may guide high-quality Cd-based crystal growth techniques. [ABSTRACT FROM AUTHOR]

The influence of ytterbium and indium on a co-doped CdZnTe (CZT:(In,Yb)) crystal grown using the vertical Bridgman method was investigated. A new energy level, mainly derived from [YBCd]+, was identified from the photoluminescence (PL) spectra. The trap density of Cd vacancies was obviously reduced along with an increased number of tellurium antisites according to thermally stimulated current (TSC) measurements. A variation in the intensity ratio for the A0X/D0X peak was observed in the PL spectra compared with an indium doped CdZnTe (CZT:In) crystal. Time-of-flight (TOF) results showed that the electron mobility was determined to be 1148 cm2 Vs−1, which is about 26% higher than that of CZT:In. The major cause was considered to be electrical compensation and the gettering process, where the concentrations of Cd vacancies and acceptor impurities were reduced, leading to an enhancement in the mobility. [ABSTRACT FROM AUTHOR]