OPTICAL CHARACTERIZATION OF AR-IMPLANTED AND ANNEALED GAAS DOPING SUPERLATTICES( ION)

Three GaAs doping superlattice (SL) structures of d(n) = d(p) = 20, 40 , 60 nm thicknesses, grown by low-pressure OMVPE on semi-insulating Ga As substrates were investigated by low-temperature photoluminescence ( PL) spectroscopy. The n-layers were doped with tellurium and p-layers with zinc, n(D) = n(A) = 1 X 10(18) cm(-3). The response of the SL sam ples to 142 and 5 keV Ar+ bombardment was studied. The high-energy 142 kV Ar+ and low dose Ar+ 10(13) cm(-2) ion implantation leads to forma tion 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 t emperature. In addition, inelastic light scattering measurements have been performed. In the untreated S2 sample for crossed polarization, w e detect three peaks (single particle excitation, spin-flip scattering processes). The frequency shifts of the observed peaks directly corre spond to the energy separation of the subbands. In the treated sample, the spin-density excitations between third and fourth subbands are st rongly enhanced. The study of the influence of annealing at several te mperatures 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 b ound with increase ion dose. (C) 1998 Elsevier Science B.V. All rights reserved.