VERTICAL GRADIENT FREEZE GROWTH OF TERNARY GASB-INSB CRYSTALS

An original vertical gradient freeze furnace was used to grow ternary GaSb-InSb crystals of indium composition ranging from 0.1% to 10%. An order of magnitude analysis showed that solute transport in the melt was mainly convective, a prediction confirmed by the shape of the experimental segregation profiles. Depending on the In content, the structural quality of the ternary crystals could be either better (low concentrations) or worse (medium concentrations) compared to pure GaSb samples grown under similar conditions. In an attempt to explain these results, the mechanical stresses due to chemical misfit were quantified through finite element calculations. We then focused our attention on the seed-crystal interfaces, and we observed experimentally a dislocation-rich layer at these locations. This would mean that the stresses linked with the composition step unavoidable in practice are accommodated plastically, an hypothesis in agreement with the theoretical predictions of the epitaxy models. © 1990.