Low Thermal Gradient Czochralski growth of large CdWO{sub 4} crystals and electronic properties of (010) cleaved surface

Journal Article · Fri Apr 15 00:00:00 EDT 2016 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2015.05.017· OSTI ID:22577806

Galashov, E. N. ^[1]; Khyzhun, O. Y.; Bekenev, V. L. ^[2]; Pokrovsky, L. D. ^[3]; Borovlev, Yu. A. ^[4]; Zhdankov, V. N. ^[5]

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1. Department of Applied Physics, Novosibirsk State University, Novosibirsk 630090 (Russian Federation)
2. Frantsevich Institute for Problems of Materials Science, NAS of Ukraine, 3 Krzhyzhanivsky Street, Kyiv UA-03142 (Ukraine)
3. Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90 630090 (Russian Federation)
4. Laboratory of Crystal Growth, Nikolaev Institute of Inorganic Chemistry, SB RAS, Novosibirsk 90 630090 (Russian Federation)
5. CML Ltd., 3 Lavrentiev Avenue, Novosibirsk 90 630090 (Russian Federation)

The crystal growth of large high-quality inclusion-free CdWO4 crystals, 110 mm in diameter and mass up to 20 kg, has been carried out by the Low Thermal Gradient Czochralski (LTG Cz) technique. The high-purity CdWO{sub 4}(010) surface has been prepared by cleavage and high structural quality of the surface has been verified by RHEED, revealing a system of Kikuchi lines. The chemical state and electronic structure of the surface have been studied using X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES). The total and partial densities of states of the CdWO{sub 4} tungstate were calculated employing the first-principles full potential linearized augmented plane wave (FP-LAPW) method. The results indicate that the principal contributors to the valence band of CdWO{sub 4} are the Cd 4d, W 5d and O 2p states which contribute mainly at the bottom, in the central portion and at the top of the valence band, respectively, with also significant contributions of the mentioned states throughout the whole CdWO{sub 4} valence-band region. With respect to the occupation of the O 2p states, the results of the FP-LAPW calculations are confirmed by comparison on a common energy scale of the XPS valence-band spectrum and the XES band representing the energy distribution of the O 2p states in this compound. Additionally, the FP-LAPW data allow us to conclude that the CdWO{sub 4} tungstate is a non-direct semiconductor. - Highlights: • Large high-quality CdWO{sub 4} crystals, up to 115 mm in diameter and mass up to 20 kg, have been grown. • The high-purity cleaved CdWO{sub 4}(010) surface has been studied by the XPS and XES methods. • The principal contributors to the CdWO{sub 4} valence band are the Cd 4d, W 5d and O 2p states.

• OSTI ID: 22577806
• Journal Information: Journal of Solid State Chemistry, Vol. 236; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CADMIUM TUNGSTATES
CHEMICAL STATE
CLEAVAGE
COMPARATIVE EVALUATIONS
CRYSTAL GROWTH
CRYSTALS
DENSITY OF STATES
ELECTRON DIFFRACTION
ELECTRONIC STRUCTURE
ENERGY SPECTRA
IMPURITIES
KIKUCHI LINES
SEMICONDUCTOR MATERIALS
SURFACES
TEMPERATURE GRADIENTS
X RADIATION
X-RAY EMISSION SPECTROSCOPY
X-RAY PHOTOELECTRON SPECTROSCOPY