Precipitate engineering in GaAs studied by laser scattering tomography

Annealing experiments were carried out with semi-insulating LEC GaAs. The volumes of the precipitates were determined by an advanced technique of laser scattering tomography (LST) qualified for quantitative volume measurements and their statistical relevant evaluation. The dependence of the volume distributions of precipitates on annealing conditions is presented. The dependence of the total volume of the precipitate ensemble on hold temperature and time is shown. The experimental results cannot be explained completely in the framework of Ostwald ripening of the As precipitates. A behaviour not described earlier has been observed: at cooling inside the assumed homogeneity range of GaAs the growth of As precipitates followed by their dissolution.