PROBING OF NEAR-SURFACE SEMICONDUCTOR LAYERS BY ELECTRON-ENERGY LOSS SPECTROSCOPY

The long-range coupling of relatively high energy electrons to dipole fields associated with plasmons and interatomic vibrations has been exploited to investigate the near surface region of semiconductor materials. HREELS experiments on p-type InSb(100), having a severely modified free-carrier concentration in the sub-surface region due to argon ion bombardment and annealing, have been carried out with primary beam energies E0 = 2-180eV. This has enabled the depth of damage to be estimated as approximately 1000 angstrom and the free-carrier depth profile to be determined. The optical phonons associated with In-Sb and Al-Sb stretching vibrations in an InSb/In0.66Al0.34Sb heterostructure have also been studied. Theoretical simulations of HREEL spectra, calculated using the dielectric approximation, show that the intensity of the phonon structure is strongly dependent on both the kinetic energy of the incident electrons and the thickness of the InSb capping layer