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Abstract: A large, crack-free CdGeAs2 single crystal measuring 15mm in diameter and 45mm in length was grown in a vertical three-zone tubular furnace by a modified vertical Bridgman method, i.e. quasi-seed technique with small temperature gradient and descending quartz ampoule. High-purity, single phase CdGeAs2 polycrystallite for crystal growth was synthesized using a rocking furnace with temperature oscillation techniques. Various measuring means, including X-ray diffractometer(XRD), Fourier transform infrared spectroscopy(FTIR), and Field emission scanning electron microscope(FE-SEM) were adopted to characterize the as-grown crystal. It is found that the cleavage plane of the as-grown crystal is {101} face; the crystal is integrated in structure and crystallized well; etch pits in the shape of pentagon on (112) face have been observed for the first time using the new preferential etchant we prepared. All these results encouragingly indicate that the modified vertical Bridgman method is a convenient and effective way for high quality CdGeAs2 crystal growth. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy (XPS) was proposed as suitable method to study the low content of impurity phases on ZnGeP 2 (ZGP) single crystals which are excellent materials in non-linear infrared fields. Besides it, X-ray diffraction (XRD) and Energy Dispersive Spectrometer (EDS) tests were carried out to characterize the components homogeneity of the crystal. It is found that impurity phases Zn 3 P 2 and ZnP 2 , which are undetectable by X-ray diffraction (XRD) method due to low content, results in the heterogeneity of components and phases of ZGP single crystal. Meanwhile, Oxides of P 2 O 5 and GeO 2 were found to exist on the surface of the crystal. [ABSTRACT FROM AUTHOR]

Single-phase AgGaGeS 4 polycrystalline materials were synthesized directly from the constituent elements by vapor transporting and mechanical oscillation method. The problem of explosions was solved by careful control of the heating and cooling cycle and adopting the two-zone rocking furnace with specially designed temperature profile. The mechanical and temperature oscillations, as well as gradient cooling, were introduced in the synthesis process. The X-ray diffraction (XRD) analysis and Energy Dispersive Spectrometer (EDS) micro analysis indicated that the synthesized compound is a single-phase AgGaGeS 4 polycrystalline material. [ABSTRACT FROM AUTHOR]

Chalcopyrite of CdGeAs 2 single crystal was grown by a modified vertical Bridgman method with sufficient size and quality, and its optical, electrical and thermodynamic properties are characterized. The transmission is recorded in the 2.3–18 μm range, and the band-gap at room temperature is at 0.56 eV. Non-ideal transparency near 5.5 μm which limited its application severely exists in the front of the crystal. The crystal is p type at room temperature with hole concentrations varying from 10 14 to 10 16 cm −3 . From the results of X-ray diffraction measurements carried out over the range 25–450 °C and thermal dilatometer tests, the thermal expansion coefficients are evaluated. And on this basis the Grüneisen parameters at different temperatures are evaluated and also exhibit anisotropic behavior ( γ a > γ c ). It is found that γ a , γ c , and γ V have some difference between these two kinds of test methods. Using these Grüneisen parameters, lattice thermal conductivities have been deduced by two correction formulas. Meanwhile, specific heat capacity and thermal conductivity of [204] have been obtained as a function of temperature by experiment. [ABSTRACT FROM AUTHOR]

Abstract: A CdSiP2 single crystal measuring 15mm in diameter and 35mm in length was grown by the modified vertical Bridgman method adopting a specially designed double-walled quartz ampoule. The as-grown crystal was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF), infrared (IR) and visible–near infrared (VIS–NIR) spectrophotometers and X-ray photoelectron spectroscopy (XPS). It is found that multiple diffraction peaks of a (101) cleavage face are evident and parallel growth steps on the face are observed. The XRF result indicates that the chemical composition of the as-grown crystal is close to the ideal stoichiometry. The IR transmittance of a sample with 2mm thickness is about 48% in the range from 10,000 to 1500cm−1. The VIS–NIR spectrum shows that the short wave absorption edge is at about 576nm and the calculated band gap is about 2.15eV. The binding energies of the Cd 3d3/2, Cd 3d5/2, Si 3d and P 2p core levels are determined to be 411.8eV, 405.1eV, 101.1eV and 129.5eV, respectively. These results show that the quality of the as-grown crystal is good and the double-walled quartz ampoule technique is promising for the growth of high-quality CdSiP2 single crystals. [Copyright &y& Elsevier]

Abstract: High-purity, single-phase CdSiP2 polycrystalline materials were synthesized directly from the constituent elements by a new method without graphite boat sealed in silica ampoule. The problem of explosions was solved by careful control of the heating and cooling cycle and adopting the two-zone rocking furnace with specially designed temperature profile. Mechanical and temperature oscillations as well as gradient cooling were introduced in the synthesis process. The mechanism and advantages of this new method are discussed. X-ray diffraction (XRD) analysis and Energy dispersive X-ray (EDX) microanalysis both indicated that the synthesized compound is high-quality CdSiP2 polycrystalline material. [Copyright &y& Elsevier]

Abstract: A high quality ZnGeP2 (ZGP) single crystal 22mm in diameter and 70mm in length was grown by a modified vertical Bridgman method. The as-grown and annealed crystals were characterized using XRD, IR spectrophotometers, positron annihilation lifetime (PAL), Hall Effect and resistivity measurements. It is found that there was a cleavage face {204} along the appearance face on the as-grown crystal. After annealing the crystal, the width of XRD rocking curve of the annealed crystal was decreased, the intensity was high and the symmetry was better than that of the as-grown crystal. The IR transmission spectrum indicated that annealing decreases significantly the optical absorption in the region of 1.3–2.6μm and transmittance exceeds 57% in the range of 3–8μm. PAL results showed that single zinc vacancies were unstable since they aggregated with each other after annealing under zinc vapor at 500°C, and both the number of single zinc vacancy and the size of large vacancy decreased under cover-up with ZGP polycrystalline powder at 600°C. The Hall effect and resistivity measurement results showed that the ZGP crystal has p-type conductivity; after annealing with ZGP polycrystalline powder the carrier concentration was decreased to 1010 cm−3 and resistivity was increased to 108 Ωcm. The above mentioned results demonstrated that annealing treatment improved significantly the optical quality of as-grown ZGP crystal; the proposed annealing process is effective and a promising new method to decrease of the point defects in the ZGP crystal. [Copyright &y& Elsevier]

Abstract: A chemical etching orientation method is suggested for the ZnGeP2 crystals. Several polished faces of ZnGeP2 crystals were etched in a certain etching solution. Some regular etch pits appeared on all samples. The indices of side facets of the etch pits were measured by X-ray rocking method, which mainly belong to {204}, {112} and {110}. Then the three crystallographic axes of the crystals were determined according to the angle relationship. Finally, optical parametric oscillator (OPO) devices were cut at the direction of θ=0° and φ=53°. [Copyright &y& Elsevier]

Abstract: The growth procedures for CdSe crystal have been optimized by thermal analysis techniques and a high-quality single crystal with large size has been grown. CdSe crystal was determined to exhibit smooth interface growth based on Jackson’s model; the growth rate equation in the vapor phase method was built and the thermodynamic parameters (activation energy and rate constant pre-factor) in the growth equation were obtained by thermogravimetic analysis of the sublimation process of the crystal. The growth rate distribution curves under various temperature differences between the source and growth region of growth ampoule were obtained, and then the growth procedures such as temperature difference, growth temperature and pulling rate were optimized. Using the optimizing vapor phase growth technique, a single crystal with 26mm diameter and 45mm length has been grown, and it was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive analyzer of X-ray and IR spectrophotometers. The results show that the as-grown CdSe ingot has prefect crystallinity, good homogeneity and high transmittance, which showed that the vapor phase growth technique optimized by thermal analysis was a promising growth method for high-quality CdSe single crystal. [Copyright &y& Elsevier]

Abstract: Good quality AgGa1− x In x Se2 (x=0.1–0.3) single crystals with 20mm diameter and 60mm length have been grown by an improved Bridgman method, i.e. descending ampoule with rotation and the real-time temperature compensation technique. The melt temperature oscillation method (MTOM) was used to synthesize high-purity single-phase AgGa1− x In x Se2 polycrystal that is free of voids. The crystallization process was carried out in the two-layer quartz ampoule with a seed pocket. The temperature gradient at the growth interface in the furnace was normally 20°Ccm−1 in the open bore, while it was 15°Ccm−1 with the ampoule in the furnace. The quality of the as-grown crystal was characterized by using X-ray diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), infrared (IR) spectrophotometer, etc. It was found that there is a {112} cleavage face in the as-grown crystal and the homogeneous growth steps on the {112} face were observed. The four-order diffraction peaks of the {101} faces were evident. The transmittance of the crystal sample of 2mm thickness is up to 65% in the region of 700–6500cm−1. The results demonstrated that the improved new growth method of AgGa1− x In x Se2 single crystals is promising and the quality of the grown crystals is good, and after annealing, the crystals can be used for IR nonlinear optical devices. [Copyright &y& Elsevier]

Abstract: A good quality ZnGeP2 (ZGP) single crystal 15mm in diameter and 40mm in length was grown in a vertical three-zone tubular furnace by the modified Bridgman method, i.e. real-time temperature compensation technique (RTTCT) with descending ampoule. The starting material is high-pure and single-phase polycrystal of ZnGeP2 synthesized by the single-temperature zone and mechanical oscillation method (STZMOM). The as-grown single crystal was characterized by various methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analyzer of X-ray (EDAX), and IR and UV spectrophotometers. It is found that there is a cleavage face of (112) and second-order XRD peaks of the {112} faces are observed, the IR transmittance of a sample of 2mm thickness is above 55% in the range from 6000 to 800cm−1, the absorption edge is near 612.5nm and the band gap is about 2.02eV. The absorption coefficient (α) is within 0.015–0.022cm−1 at the spectral region 2–8μm. The crystal has a stoichiometry ratio Zn:Ge:P=1:1.12:1.91 which is close to the ideal stoichiometry ratio of 1:1:2. All results demonstrate that the modified growth method is a new and promising method for the ZGP single crystal and the quality of as-grown crystal is good. [Copyright &y& Elsevier]