Authors: Huan Yong Li, Ke Wei Xu, Wan Qi Jie
Abstract: Two chemical vapor transport methods with Zn(NH4)3Cl5 transport agent were developed to grow ZnSe bulk single crystals. Two kinds of Zn-rich ZnSe single crystals, conical crystal and flake crystal,were grown directly from untreated ZnSe polycrystals and two elements, respectively. The structure characters, purity and etch pit density were studied by rotating orientation XRD, PL spectrum and optical microscope. The contrastive investigation between two growth results indicated that the conical crystal was composed of (111) and (100) faces, and the flake crystal exhibited only (111) face. Moreover, the vicinal interface leaning to (111) face by the angle of 3.1° was the dominative growth face in vapor growth system, and growth occurs by layer-by-layer model. FWHM of RO-XRD pattern of ZnSe (111) face was 24sec for conical ZnSe crystal and 48s for ZnSe flake crystal. The results suggested that high-quality ZnSe crystals can be grown from the chemical vapor transport method with Zn(NH4)3Cl5 transport agent.
1689
Authors: Xin Zhao, Ying Rong Jin, Xing Hua Zhu
Abstract: High-pure and single-phase PbI2 polycrystal was synthesized by Pb and I elements (99.9999%) according to the stoichiometry of PbI2 with excess of 0.3% Pb through modified two-zone vapor-transporting method (MTVM). The synthesis reaction was carried in a special quartz ampoule to prevent the ampoule exploding by controlling the temperature. With presynthesized polycrystal, an integral PbI2 single crystal with 15 mm in diameter and 25 mm in length was grown by vertical Bridgman method (VBM). The as-grown crystal was characterized by X-ray diffraction (XRD), ZC36 megger and Infrared (IR) spectrophotometers. XRD analysis indicated the structure of PbI2 crystal is 2H with hexagonal space group of , the lattice constants of a and c are 0.4560 nm and 0.6979 nm, respectively. The IR transmittance of a sample of 2.5 mm thickness is about 40% in the range from 4000 to 400 cm-1. Resistivity of the crystal is about 1013 Ωcm magnitude. These results demonstrate that the quality of the as-grown crystal is high enough for applications of room temperature nuclear radiation detectors.
720
Authors: Xin Zhao, Shi Fu Zhu, Yong Qiang Sun
Abstract: In order to meet the requirements of growing high-quality ZnGeP2, a crystal growth furnace with three-temperature-zone was designed and fabricated based on a conventional vertical two-zone tubular resistance furnace. Appropriate temperature gradients of 12~15°C/cm at the growth interface and stable thermal profile were obtained. A crack-free ZnGeP2 single crystal with size of Φ15mm×30mm was grown successfully in the furnace mentioned above. The as-grown crystal was characterized by X-ray diffraction (XRD) and Infrared (IR) spectrophotometers. It is found that there is a cleavage face of (101) and X-ray multiple diffraction peaks of the {101} faces are observed, The infrared transmission of a ZnGeP2 wafer of 3 mm thickness is about 50% in the region of 3~10μm. These results show the designed crystal growth furnace is suitable for growth of ZnGeP2 crystal, and the as-grown ZnGeP2 crystal has good structural integrity and high quality.
945
Authors: Zhi Ping Zheng, Jing Wang, Lin Quan, Shu Ping Gong, Dong Xiang Zhou
Abstract: Electro Dynamic Gradient (EDG) method was utilized for TlBr crystal growth in this paper. The influence of crystal growth conditions such as temperature gradient and growth rate on optical and electrical properties of grown TlBr crystals was investigated. The quality of TlBr crystals was characterized by infrared (IR) transmittance spectrum, X-ray diffraction, and I-V measurements.
1979
Authors: Jing Liu, Yu Zhang
Abstract: Lead iodide (PbI2) single crystal for room temperature radiation detectors are mainly produced by Vertical Bridgman (VB) method. Computer simulations of the VB method could be an effective tool to optimize the growth process and reduce the production costs. In the present study, we applied the general Computational Fluid Dynamics (CFD) code to solute the quasi-static two-dimensional (2D) axisymmetric model of the VB ampoule filled with PbI2 melt and direct the growth of high quality PbI2 single crystals with a diameter of 15 mm. The thermal conductivity and latent heat generation during the crystallization is considered in the numerical model. We focused on the crystal-melt interface deflection. The results demonstrated that the ampoule with 15 mm diameter is better than that of 30 mm. The experimental results showed that the single crystal with 15 mm diameter exhibited high electrical resistivity (109 Ωcm).
58