A. Cricenti et Ac. Felici, SURFACE DIELECTRIC FUNCTION OF CDTE(110) OBTAINED BY POLARIZED SURFACE DIFFERENTIAL REFLECTIVITY DATA, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 13(4), 1995, pp. 1913-1916
Citations number
17
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
We present a determination of the complex surface dielectric function
(SDF) of CdTe(110) obtained by using polarized surface differential re
flectivity (SDR) data. The analysis of SDR data is done in the framewo
rk of a macroscopic three-layer model in which the media involved (vac
uum, surface, and substrate) are assumed to have definite anisotropic
functions. A relation between SDR data and the complex SDF is obtained
under the assumption that the oxide layer is nonabsorbing in the rang
e explored. From the experimental data SDF has been computed for light
electric vector along [1(1) over bar0$] and [001] directions, i.e., p
arallel and perpendicular to the natural chains of the unreconstructed
(110) surface. In the energy range below 3.3 eV the imaginary part of
SDF (epsilon(s)'') and SDR data are very similar while above 3.3 eV t
hey differ markedly because of the effect of bulk contribution. Three
mainly isotropic structures are clearly visible in the deconvolved eps
ilon'' spectra at the following photon energies: 2.7, 3.3, and 3.7 eV.
Such structures are interpreted in terms of optical transitions betwe
en surface state bands as derived from direct and inverse photoemissio
n. The transition at 2.7 eV is assigned at the Gamma point in the surf
ace Brillouin zone, the one at 3.3 eV at the Gamma and X while the one
at 3.7 eV at the X and X'. The effective number of electrons per atom
participating in the optical transitions is calculated for energies u
p to 4.0 eV resulting in slightly more than 0.5. (C) 1995 American Vac
uum Society.