Introduction of defect clusters in GaAs by high-energy γ-rays

The origin of the defects responsible for the variation in the electrical properties of GaAs (n0 = 1013 to 6 × 1015 cm−3) due to irradiation with γ-rays of 28-MeV electron stopping spectrum is studied. The dependence Δμ−1/Δn = f(n0) for isolated defects and defect clusters is analyzed. The comparison of the changes in the crystal electrical properties due to irradiation by γ-rays of stopping spectrum with the corresponding changes induced by 60Co γ-ray and fast neutron irradiations is made. It is shown that the variation of the charge-carrier concentration following irradiation with γ-rays of the stopping spectrum is due to isolated defects, while the mobility variation is entirely attributed to defect clusters. The relation between the contributions of isolated defects and defect clusters to the change of GaAs electrical properties over a wide range of initial charge-carrier concentrations (n0 = 1013 to 1018 cm−3) is discussed.