We investigated high-resistivity cadmium zinc telluride (CdZnTe):In single crystals annealed in hydrogen to reveal the passivation effect of defects. An overall reduction in the concentration of defect levels induced by annealing was obviously observed by thermally stimulated current measurements. There is a large decrease by 56.51% in the concentration of secondly ionized Cd vacancies (T3) after hydrogenation. The concentration of firstly ionized Cd vacancies (T2) was a little bit lower (17.99%) in the hydrogenated CZT crystals. The formation of neutral InH complex and lower occupation of VCd by In dopant would result in a significant decrease (68.31%) in the trap density of ${\rm In}_{\rm Cd}^ +$ related shallow donor (T1) after hydrogenation. The bulk resistivity was calculated from I–V characteristic curves to be ~1.97 × 1010 Ωcm before annealing and ~1.78 × 1010 Ωcm after annealing. Hall measurements also reveal n-type conduction for the hydrogenated crystals. Electron mobility was fitted to be about 110 cm2/Vs before annealing and 488 cm2/Vs after annealing, demonstrating better carrier transport properties. Electron mobility-lifetime product could be fitted to be about 3.60 × 10−4 cm2/V before annealing and 5.45 × 10−4 cm2/V after annealing, demonstrating better detector performances.

It has been demonstrated that the introduction of NaCl can significantly improve the quality of monolayer WS2 at the growth temperatures ranging from 700°C to 850°C by atmospheric pressure chemical vapor deposition (APCVD) without the assistant of hydrogen. Here, the influence of NaCl on the nucleation and growth of WS2 has been thoroughly investigated. The morphology and quality of WS2 grown with different temperatures are discussed by optical microscope, Raman and Photoluminescence (PL) spectra. It was found that amount of NaCl can efficiently influence the morphology and quality of WS2 crystals. PL intensity of WS2 crystal increases around three times from the center region to the edge of an individual domain, which may be attributed to the appearance of small triangle hollows formed during the growth at the edge of single crystal WS2.

A transmission electron microscopy (TEM) study on defects in a 30 μm-thick epitaxial CZT film deposited on (001)GaAs via close-spaced sublimation was performed. The epi-layer is of good quality without twins. Dislocations and stacking faults are mainly gathered near the interface. The dislocations are extrinsic either of Lomer edge or 60° type. Pseudo extrinsic stacking faults consisting of two independent and oppositely oriented extrinsic dislocations have been found both on the (111) and the planes. L-shaped defects originated from the interface have been discovered. The near-interface-side of L is consisted of 3 compressed (111) planes and the lateral side is consisted of 3-4 misarranged planes. This L-shaped defect is induced by the absence of a misfit dislocation at the intersection between L and the interface.

In-depth studies of the two types of Te nanoprecipitates, linear and elliptic, in Cd1–xZnxTe (CZT) crystals grown by a modified vertical Bridgman method have been carried out. Electron diffraction suggests that linear Te nanoprecipitates align their Te atoms in a similar way to CZT structure, while elliptic Te nanoprecipitates cluster Te atoms following the pure trigonal Te structure. The three-dimensional morphology for both linear and elliptic Te nanoprecipitates has been revealed by delicate energy-dispersive x-ray analysis under electron microscopy. The density of elliptic Te nanoprecipitates ranges from 1015 to 1017 cm−3, while linear ones usually several times lower for a certain CZT wafer. The origin of both types of Te nanoprecipitates has been discussed in terms of the local density of intrinsic point defects in CZT. CZT properties are influenced more negatively by elliptic Te nanoprecipitates, which shed light on the methodology for crystal growth: preventing the clustering of intrinsic point defects during the crystal growth will be essential to obtain high quality CZT crystal.

The clean and ordered surfaces of CdZnTe (111)B grown by the Bridgman method were obtained by Ar ion bombardment and thermal annealing in situ in an ultrahigh vacuum. The surface atomic structures of CdZnTe (111)B after annealing at different temperature were observed by low-energy electron diffraction (LEED). The valence band and work function of CdZnTe (111)B surfaces were determined by synchrotron radiation photoemission spectroscopy. The order of CdZnTe (111)B after annealing at 350 °C will worsen, and the (111)B-(2 × 2) local reconstruction will be formed. The work function of CdZnTe (111)B after annealing at 350 °C is 0.8 eV higher than that of CdZnTe (111)B-(1 × 1), and the local reconstruction may be induced by Te adatoms on top of the ideal truncation.

Temperature-dependent photoluminescence (PL) spectra were measured to characterize the In-doped cadmium zinc telluride (CdZnTe, or CZT) crystals along the growth direction in the range of 10 to 60 K. High-resistivity CZT samples with 1.2 ppm In dopant at the tip and low-resistivity samples with 60 ppm In dopant at the heel have been assessed. The PL intensity quenching of D0X were fitted with two activation energies for high-resistivity CZT sample and only one activation energy for low-resistivity sample, respectively, suggesting different recombination mechanisms. The C-line was observed in the PL spectra of low-resistivity CZT sample and considered to the results of the isoelectronic complexes, InCd–VCd–InCd, while in high-resistivity CZT sample, shallow donor accepted pair (DAP) transition was identified, and thought to be related to InCd–VCd. The A-center in PL spectra was observed in low-resistivity CZT sample, which is indicative of more cadmium vacancies. It turns out that indium in low-resistivity CZT sample has not been doped as efficiently as in high-resistivity CZT sample because of the self-compensation.

CdZnTe:In single crystals were annealed in CdZn vapors through a method involving a high-temperature step and a low-temperature step in sequence. The effects of annealing on the properties of CdZnTe:In were characterized with photoluminescence (PL) spectra. The neutral acceptor bound exciton (A0, X) peak, which was on the right shoulder of the neutral donor bound exciton (D0, X) peak, disappeared after annealing. A fine donor-acceptor pair structure and its longitudinal optical phonon replicas were clear before annealing. However, both of them became undistinguishable in the PL spectrum of annealed CdZnTe:In. The two phenomena imply that the annealing treatment can remove the impurities from CdZnTe:In wafers effectively. In addition, the intensity of Dcomplex band fell remarkably after annealing, which confirmed that Cd vacancies were well-compensated in the annealing treatment.