Optical characterization of Ar+ ion implanted and annealed GaAs doping superlattices

Three GaAs doping superlattice (SL) structures of dn=dp=20, 40, 60 nm thicknesses, grown by low-pressure OMVPE on semi-insulating GaAs substrates were investigated by low-temperature photoluminescence (PL) spectroscopy. The n-layers were doped with tellurium and p-layers with zinc, nD=nA=1×1018 cm−3. The response of the SL samples to 142 and 5 keV Ar+ bombardment was studied. The high-energy 142 kV Ar+ and low dose Ar+ 1013 cm−2 ion implantation leads to formation of a new optically active band at 1.443 eV in the sample with the shortest layer thickness 20 nm. The new band is highly sensitive to temperature. In addition, inelastic light scattering measurements have been performed. In the untreated S2 sample for crossed polarization, we detect three peaks (single particle excitation, spin-flip scattering processes). The frequency shifts of the observed peaks directly correspond to the energy separation of the subbands. In the treated sample, the spin-density excitations between third and fourth subbands are strongly enhanced. The study of the influence of annealing at several temperatures by low-temperature photoluminescence spectroscopy has shown that the samples can be recovered. Five keV Ar+ bombardment leads to a broadening and decrease in intensity of the electron–zinc acceptor bound with increase ion dose.