THERMODYNAMIC ASPECTS OF (TE,S)-DOUBLE-DOPED GASB CRYSTAL-GROWTH

A series of GaSb single crystals double doped with tellurium and sulph ur were grown using the Czochralski method without encapsulant in an a tmosphere of flowing hydrogen. The Hall carrier concentration of these crystals was measured and compared with the calculated values. Very g ood agreement appeared for the sulphur concentration C(S) for total am ounts of dopants (Te and S) smaller than 12 at.%. If C(S) exceeds a va lue of 12 at.%, the theoretical and practical values of the Hall conce ntration differ from each other. It seems that this effect was caused by the creation of a Te-S solid solution and by the subsequent elimina tion of dopants from the GaSb lattice. This assumption is supported by measurements of dislocation density. In the case of C(S) greater than or similar to 12 at.% the dislocations were uniformly distributed on the surface of GaSb[111] samples because the so-called ''glide phenome na'' could be suppressed by the formation of some precipitates of the Te-S solid solution which might generate dislocations in the whole vol ume of the GaSb single crystals.