Influence of indium doping on the formation of silicon-(gallium vacancy) complexes in gallium arsenide grown by molecular-beam epitaxy at low temperatures

Low-temperature photoluminescence (PL) studies of gallium-arsenide layers grown by molecular-beam epitaxy at low (200 deg. C) temperatures (LT GaAs) and doped with silicon or a combination of silicon and indium have been performed. The PL spectra of as-grown samples reveal a shallow acceptor-based line only. After annealing, an additional line at ∼1.2 eV appears, which is attributable to SiGa-VGa complexes. The activation energy of complex formation is found to be close to the activation energy of migration of gallium vacancies and is equal to 1.9±0.3 eV for LT GaAs : Si. It is found that doping with a combination of silicon and indium leads to an increase in the activation energy of formation of SiGa-VGa complexes to 2.5±0.3 eV. We believe that this increase in the activation energy is controlled by the gallium vacancy-indium interaction through local lattice deformations