Detached phenomenon: Its effect on the crystal quality of Ga(1−x)InxSb bulk crystal grown by the VDS technique

Vertical directional solidification (VDS) technique is used on the combined growth principals of the conventional methods since 1994, which leads to the detached growth. For evaluation of the detached growth, five bulk ingots of indium doped gallium–antimonide GaSb:In (In = 0.5, 0.25, 0.15) have been grown – without the seed, without contact to the ampoule wall, without coating and without external pressure. The gap is attributed to compensate the differential thermal dilatation that is grown with the reduced diameter than the diameter of the ampoule. VDS experiments have been proved that the sum of the contact angle and growth angle is large enough to allow detachment without any additional pressure difference under the melt to offset hydrostatic pressure. A meniscus forms at the bottom of the melt, the capillarity effect establishes due to which spontaneous gap could be created by the melt free surface, thus no thermal shear stress and thermo-mechanical stresses at the interface. Detached grown bulk GaSb:In crystals showed superior crystal quality with the highest physical properties and mobility than the crystals grown ever. The axial and radial composition profile of the grown GaSb:In ingots showed variation ≤10%. From the conical region, dislocation density decreases in the growth direction and reaches less than 103 cm−2.

► Detachment: without seed, without ampoule contact, without coating, without external pressure.
► Detached ingot growth samples showed the highest physical properties and the carrier mobility.
► Initial to final transition: in detached growth, dislocations decreases and less than 103 cm−2.
► Detached samples: Raman spectrum shows only TO phonon (110) direction of single orientation.
► Detached ingot: FTIR shows highest transmissions % but decreases on increase doping in samples.