Growth and Dislocation Structure of Single-Crystal Ga (As1−xPx)

The preparation of single-crystal GaAsP by halide vapor transport is described. That dislocation free GaAsP can be achieved was verified experimentally for whiskers grown by the vapor-liquid-solid method. In the growth of monocrystalline ingots for device purposes, growth mechanics and the resulting crystal habit are strongly influenced by degenerate Zn, Te, and Se doping. Since n-type crystals require higher supersaturations, single-crystal growth is easier to obtain with Zn doping. The as-grown dislocation structure of ingots with low-index natural facets is examined by decoration and etching. Typical densities are 5×103 to 106/cm2. From their simple crystallographic orientations different dislocations are identified. 〈211〉, {111} and 〈100〉, {110} edge dislocations are observed in {110} polygonization walls. Values of mobility and carrier density are evaluated from a device point of view. Laser diodes with threshold currents as low as 3000 A/cm2 at 33.3% GaP have been obtained from this material.