STRUCTURAL AND ELECTRONIC EFFECTS OF ARGON SPUTTERING AND REACTIVE ION ETCHING ON IN0.53GA0.47AS AND IN0.52AL0.48AS STUDIED BY INELASTIC LIGHT-SCATTERING

The effects of Ar sputtering and HBr reactive ion etching on In0.53Ga0.47As and In0.52Al0.48As epitaxial layers were investigated by Raman spectroscopy. First-order phonon scattering was used as a probe of structural modification, while coupled phonon-plasmon mode scattering was used to investigate electrical modification. Second-order phonon scattering proved insensitive to sputter- and etch-induced structural modification. For both In0.53Ga0.47As and In0.52Al0.48As, Ar sputtering leads to more structural modification than does HBr etching, the difference being greater for In0.53Ga0.47As. In0.52Al0.48As exhibits a greater resistance to sputter-induced structural damage than does In0.53Ga0.47As, and nominally undoped material displays less susceptibility to being disordered structurally than does more highly doped material for both In0.53Ga0.47As and In0.52Al0.48As. HBr etching results in no electrical modification of In0.53Ga0.47As, whereas a decrease in carrier density and/or an increase in plasmon damping is observed in In0.52Al0.48As. Annealing In0.52Al0.48As under conditions known to restore electrical activity of dopants in GaAs and Al0.3Ga0.7As results in no change in the coupled mode spectra, indicating that electrical modification is not due to hydrogen passivation of dopants.