Positron Study of Vacancy-Type Defects Induced by Heavy Doping into MBE-Grown GaAs

Abstract
Variable-energy positron beam studies have been carried out on heavily Si-doped GaAs/AlGaAs/GaAs specimens prepared by molecular beam epitaxy. From the measurements of Doppler broadening profiles of the positron annihilation as a function of the incident positron energy, it was found that Ga vacancies with very high concentration are introduced in the GaAs layer by the heavy doping of Si. It was concluded that a Ga vacancy acts to reduce the concentration of free carriers.