INSITU DETERMINATION OF ELECTRONIC-PROPERTIES OF CLEAN GAAS(100) SURFACES BY HIGH-RESOLUTION ELECTRON-ENERGY LOSS SPECTROSCOPY

The surface electronic properties such as depletion layer thickness, surface potential, plasmon lifetime and electron density are systematically studied by analyzing surface phonon and plasmon excitations in high-resolution electron-energy-loss spectra (HREELS) on n-type GaAs(100) surfaces immediately after MBE growth. Explicit and simple formulae are deduced to determine the surface electronic properties from the HREEL spectra and their validity is discussed. A probing depth for HREELS is determined experimentally and its applicability is discussed. The surface electronic properties derived from the HREEL spectra are cross-checked by using the results obtained by the Hall and ultraviolet photoelectron spectroscopy measurements. Thus the versatility of HREELS is demonstrated as an in situ characterization of semiconductor surfaces.