Inelastic electron scattering from clean and arsenic overcoated GaAs(100).

High resolution electron energy loss spectra have been recorded for the (4x6), c(2x8), and c(4x4) surface reconstructions of GaAs(100). Spectra were also measured following the deposition of As sub 2 and As sub 4 molecular species at 100K onto the c(2x8) reconstructed surface for coverages ranging from 0. 25 to 6 monolayers. For the clean surface reconstructions, low frequency quasielastic scattering increases systematically and reproducibly in the order (4x6) c(2x8) c(4x4). Arsenic dimer deposition induces additional quasielastic scattering which is approximately linear in the arsenic coverage, whereas tetramer deposition displayed minimal linewidth broadening for coverages below ~3 monolayers.