Single crystals of GaSb have been grown by the Czochralski method under reducing conditions. Crystals were grown in the (loo>, <111>, and <112) directions. The (111) growth direction was found to be the most suitable for the successful and reliable crystal growth. Dislocation densities in (11 1)

GaSb single crystals codoped with tellurium and sulphur were studied by capacitance transient methods. The tellurium doping allowed us to have the free carrier concentration about ten times higher than the sulphur one and in this manner to ensure appropriate conditions for measurement of the sulphur-related deep donor (DX-like level). Emission and capture barriers were determined; the value of the former was found to be different from that measured on GaSb:S samples. The shape of the transients was examined and described by the Gaussian broadening of the barrier energy. The emission transients were discovered to be nearly exponential (Gaussian broadening energy E < 5 meV) while the capture process was strongly non-exponential ( E = 25-30 meV). The non-exponentiality was explained by a spatial variation of the capture barrier due to the fluctuating potential of the shallow charged impurities.

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A series of GaSb singie crystais doped with manganese was grown by the Czochralski method without encapsulant in a flowing atmosphere of hydrogen. From Hall and conductance measurements it has been fo,und that manganese creates shallow acceptors with an activation energy of 16 i-2 meV, which strongly enhance conductivity at low temperatures. Using the values of Hall concentrations in the samples cut from the grown crystals, the manganese distribution coefficient in GaSb was caicuiaied to be 0.0ii i: 0.00i ior V n concentration in the meit wiiiin the range 7.0 x 1OZ4-9.7 x lOZ5atoms/m3.