Accumulation of vacancy complexes in magnesium-doped silicon upon irradiation

The effect of Mg impurity on the processes of accumulation of the compensating radiation defects in epitaxial layers of Silicon has been studied. The experiments have been performed with the phosphorus-doped layers of n-type Silicon (ρ = 1-20 Ω * cm) produced by the gas-phase epitaxy at inverse substrates. In the process of growth the epitaxial layers were additionally doped with magnesium. The epitaxial Silicon layers grown in the identical conditions but without Mg-doping were used as the reference ones. Irradiation (Tir≤50o C) was effected by α-particles from the 210Po isotope source or by γ-quanta of 80Co. Hall measurements (Van Der Paw method) of the temperature dependences for the carrier charge concentrations over the range Tmeas = 80- 400 K have been performed at different stages of irradiation. Based on analysis of the results obtained, the energy spectrum of compensating radiation defects levels has been determined, and proved to be identical in the reference and examined samples. For both types of irradiation most effectively formed were the defects, contributing to the bandgap those energy levels (Ec - 0.18 eV and >Ec-0.30 eV) which are associated with A- and E-centers, respectively. It has been fond that (1) rate of the E-center formation is strongly dependent on the phosphorus content; (2) higher rates of the E-center formation are observed in the epitaxial layers with Mg impurity present; (3) efficiency of the A-center introduction somewhat lowers with the increased concentration of phosphorus, being higher in the epitaxial layers under study as compared to the reference ones. The obtained results have been interpreted with due consideration for compensation of the surface-created deformation stresses by Mg atoms