Small angle scattering experiments on annealed gallium arsenide single crystal wafers

The minimum concentration of excess atoms precipitated in GaAs and InP being necessary to cause observable small angle scattering of X-rays and neutrons (SAXS and SANS, respectively) was estimated. Consequently, undoped melt-grown GaAs wafers were annealed at high arsenic pressure. Areas of a strongly increased density of precipitate were localized by transmission electron microscopy. SAXS experiments have revealed a very weak intensity being dependent on energy at values of the scattering vector Q>0.02 Å^-1. Different annealing procedures have resulted in distinguishable curves of SANS (Q<0.03 Å^-1) in dependence on temperature and arsenic pressure