Electrical properties of GaSb-InSb alloys

Abstract

Reasonably homogeneous, polycrystalline, solid ingots of GaSb-InSb alloys have been produced by slow directional freezing techniques, and have been used to investigate the variation of electrical properties as a function of composition. Values of extrapolated thermal energy gap E 0, electron mobility, and mobility ratio have been determined for some 25 specimens covering the complete composition range. Estimates have been made of the variation of effective mass values and, by comparison with optical energy gap values, of the energy gap temperature coefficient β. From the variation of mobility with temperature, values of mobility temperature exponent x have been obtained. At the InSb-rich end of the composition range, the results indicate a smooth variation of the various parameters with composition, without any appreciable change in the band structure from that of InSb. The results at the GaSb-rich end of the range are complicated, firstly by the presence in GaSb of two conduction bands of only small energy separation, and secondly by an effect which extends over a considerable range of composition and is thought probably to be due to ordering in the alloys. As a result, correlation of the optical and electrical results is difficult in this range of composition.