GROWTH OF TWIN-FREE CDTE SINGLE-CRYSTALS IN A SEMICLOSED VAPOR-PHASE SYSTEM

V and Ga doped CdTe single crystals with one inch diameter were grown without wall contact in a semi-closed vapour phase system (modified Ma rkov method). By vapour transport modelling, we demonstrate that volat ile impurities and excess species are enabled to condense in a heal si nk connected to the growth chamber. Vapour composition and component f luxes are controlled by the temperature profile, in particular by the sink temperature. The grown crystals exhibit pronounced {111}, {110} a nd {100} facetting. The influence of the deep heat sink on interface s tability is discussed in terms of growth morphology and formation of i nclusions. Piezobirefringence measurements indicate nearly stress-free growth. The resistivities of the grown crystals are up to 3 x 10(9) O mega.cm.