ABSTRACT
In order to further our research into uncooled Indium Antimonide based detectors and emitters, we require to reduce the cut-off wavelength below the 7μm room temperature cut-off wavelength of indium antimonide, into the 3-5μm atmospheric window. The approach we have chosen is to use the ternary alloy semiconductor indium aluminium antimonide, because of its rapid change of energy gap as a function of lattice parameter, grown onto a lattice matched substrate The substrate we have chosen to use is indium gallium antimonide because it has a narrower liquidus-solidus separation than indium aluminium antimonide. The change of melt composition during growth, due to the liquidus-solidus separation, is minimised by the use of a double crucible technique. We have developed a novel design of double crucible which has overcome difficulties associated with the liquidus-solidus temperature difference, friction between the inner and outer crucible, location of the inner crucible, back diffusion between the two crucibles, and freezing of the channel between the two crucibles. Simple means of fabricating the channel between the two crucibles and filling it with melt have been devised. Loss of crucibles due to expansion on freezing after growth has been eliminated. Use of the double crucible technique reported eliminates the need for ternary seeds to achieve lattice matching at seed-on and also the need for precise knowledge of the distribution coefficient. [111] parallel-sided, single crystals ofIn1-xGaxSb with 0<x<0.11, up to 24 mm in diameter and 5cm long, with dislocation densities of 2.104/cm2 and composition variation of better than 10% over the majority of the crystal, have been grown and assessed for lattice-matched epitaxy of indium aluminium antimonide alloys. Epitaxy on such crystals is expected to broaden the available wavelength and lead to improved leakage currents and other parameters in diodes, lasers, FETs, and detectors.
