Seeded-vapour-phase free growth and characterization of ZnTe single crystals

A seeded-vapour-phase free growth (SVPFG) technique for obtaining large (40 -50 mm in diameter) substrate-quality ZnTe single crystals is described. To provide high structural perfection of crystals, two main methods were appl ied. (i) The use of small area (1-2 cm(2)) seeds in combination with a temp erature regime that provides simultaneous tangential and normal growth of a crystal. This allowed to decrease an effect of seed quality on the structu re of growing crystal. (ii) The use of a reverse temperature gradient betwe en the seed and support pedestal. This allowed to avoid sticking a growing crystal to the pedestal and to decrease the contact area between them. The ZnTe crystals obtained were twin free. Ech pit density was about 10(4) cm(- 2). The full-width at half-maximum of the X-ray rocking curve was 18-22 arc sec. The specific resistance was 4-20 Ohm cm. To remove Te precipitates obs erved in as-grown crystals, annealing in liquid Zn or Zn vapour was used. T he removal of the Te precipitates correlates with decrease of acceptor rela ted emission and increase of free exciton emission in the low-temperature c athodoluminescence spectra. (C) 2000 Elsevier Science B.V. All rights reser ved.