Low-temperature grown III-V materials

A new kind of semiconductor composite material is demonstrated with a dispersion of semimetallic particles with properties common to high-quality single crystals. These materials are arsenides such as GaAs, AlGaAs, and InGaAs containing arsenic clusters. The composites are formed by incorporating excess arsenic in the semiconductor, which percipitates in the anneal. The incorporation of the excess arsenic is accomplished by molecular beam epitaxy at low substrate temperatures. The cluster density can be controlled with the coarsening annealing. The positioning of the clusters can be controlled with heterojunctions and doping. These composites exhibit several interesting properties, including high-resistivity, appreciable optical absorption below the band gap of the semiconductor matrix material, a large electro-optic effect, and very short carrier lifetimes.