Φ140 mm sapphire crystal growth by temperature gradient techniques and its color centers

Sapphire crystals, 140 mm in diameter and 90 turn in height, have been grown by temperature gradient techniques (TGT). The growth direction of the boule was fixed by means of Lane X-ray diffraction. A prominent 204 nm absorption band in TGT-Al2O3. which does not appear in single crystals grown by Czochralski method has been studied. Analysis further substantiates the F-center model of this band. Two relatively weaker bands absorbing at 232 nm and 254 nm were ascribed to F+ centers. F-type centers concentration was determined using Smakula's equation. (c) 2005 Elsevier B.V. All rights reserved.

[1]  W. D. Compton,et al.  Threshold Energy for Lattice Displacement inα-Al2O3 , 1960 .

[2]  G. W. Arnold,et al.  Atomic displacement and ionization effects on the optical absorption and structural properties of ion‐implanted Al2O3 , 1974 .

[3]  K. Nassau.  Ruby and sapphire: L. M. Belyaev, ed. Amerind pub. Co., New Delhi (1980). Available from the U.S. Dept. of Commerce, National Technical Information Service, Springfield, Virginia 22161, as Document TT-52020. 443 pp. Price: $32.00 , 1981 .

[4]  T. J. Turner,et al.  Nature of the 6.1-eV band in neutron-irradiated Al 2 O 3 single crystals , 1976 .

[5]  W. B. Fowler,et al.  Physics of color centers , 1968 .

[6]  J. H. Crawford,et al.  Electron centers in single-crystal Al 2 O 3 , 1977 .

[7]  M. Stapelbroek,et al.  Optical properties of theF+center in crystallineAl2O3 , 1978 .

[8]  J. H. Crawford,et al.  Additive coloration of sapphire , 1978 .

[9]  G. Dienes,et al.  Shell-model calculation of some point-defect properties in. cap alpha. --Al/sub 2/O/sub 3/ , 1975 .

[10]  D. L. Dexter.  Absorption of Light by Atoms in Solids , 1956 .

[11]  C. P. Khattak,et al.  Current Status Of Sapphire Technology For Window And Dome Applications , 1989, Defense, Security, and Sensing.

[12]  Jun Xu,et al.  Growth of large-sized sapphire boules by temperature gradient technique (TGT) 1 Supported by the Nat , 1998 .

[13]  V. Borodin,et al.  Void formation upon annealing of shaped sapphire crystals , 1990 .

[14]  D. Staudte,et al.  Electrical and structural assessment of CdTe and CdMnTe layers grown by MBE on InSb substrates , 1990 .

[15]  P. W. Levy.  Color Centers and Radiation-Induced Defects in Al 2 O 3 , 1961 .