Defect formation in subsurface Be+-and Se+-doped GaAs layers

Abstract

The structure of subsurface Be+ and Se+ doped GaAs layers was studied by the X-ray diffraction technique. The implantation of Be+ ions into gallium arsenide substrates causes the formation of distorted layers with elastic strains. With an increase of the energy of implanted ions from 50 to 100 keV, the maximum distortion remains almost constant, whereas the thickness of the distorted layer, with a lattice constant which exceeds that of the host material, increases. At higher energies (≥150 keV), the thickness of the distorted layer continues increasing, but the maximum strain drops. The Se+ ions implantation into the GaAs substrates also provides the formation of layers distorted by positive tensile strain. The analysis of defect distributions and concentrations at various irradiation doses and the implanted-ion energies shows that the latter does not considerably affect these parameters. At the same time, an increase of the implanted-ion dose from 5 × 1014 to 5 × 1015 cm−2 increases the strains observed. The role of the Frenkel-pair annihilation and ion channeling in the formation of a defect layer is also discussed.