Surface excitations in electron backscattering from silicon surfaces

2009

The surface excitation parameter (SEP) is theoretically calculated for 12 semiconductors (GaN, GaP, GaSb, GaAs, InSb, InAs, InP, SiC, ZnSe, ZnS, Si and Ge) and for Ni (which is usually used as a reference in experiments) for electron energies between 300 eV and 3400 eV, and for angles between 0• and 70• to the surface normal. We use our previous definition of SEP, as the change in excitation probability, for an electron, caused by the presence of the surface in comparison with an electron moving the same distance in an infinite medium. The calculations are performed within the dielectric response theory by means of the QUEELS-ε(k, ω)-REELS software determining the energy-differential inelastic electron scattering cross-sections for reflection-electron-energy-loss spectroscopy (REELS), and for which the only input is the dielectric function of the medium. By fitting to these SEP values as well as our previous ones, i.e. from 27 materials, including metals, oxides, polymers and semiconductors, we also establish a simple equation depending on the generalized plasmon energy and the energy band gap of the material which allows to estimate the SEP when the dielectric function is not available.

show abstract

Section: Introductionmentioning

confidence: 99%

Surface excitation parameter for 12 semiconductors and determination of a general predictive formula

2009

show abstract

“…It has been shown 7,8 that one of the reasons for this deviation originates from surface excitation effects, i.e. the surface plasmons, neglected in theoretical calculations.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the surface excitation parameter from reflection‐electron‐energy‐loss spectra

Yubero

2005

“…With our definition of SEP, we have removed all ambiguities for the use of SEP in EPES Monte Carlo simulations. Indeed, in EPES, the total attenuation of the elastic peak intensity is expressed as [4,20] exp(−P s (E, θ in )) exp(−d/IMFP inf ) exp(−P s (E, θ out )) where P s (E, θ in ) and P s (E, θ out ) are SEP for incoming and outgoing electrons respectively, IMFP inf is the IMFP in the infinite bulk medium and d is the distance the electron has traveled inside the solid. However, if a spatial extension of the surface area is considered, this formulation is very doubtful.…”

Section: Model and Resultsmentioning

confidence: 99%

“…These surface excitations have been the object of intensive research for several years (see for instance Refs [1,2] and references therein). Indeed, it has been shown [3,4] that the energy lost during these excitations significantly influences the measured peak intensities of surface-sensitive spectroscopies as XPS, AES, elastic peak electron spectroscopy (EPES), or reflection-electronenergy-loss spectroscopy (REELS).…”

Section: Introductionmentioning

confidence: 99%

Calculation of the angular distribution of the surface excitation parameter for Ti, Fe, Cu, Pd, Ag, and Au

2008