D.J. Wentink

Full microscopic treatment of the optical response of the Si(100)2x1 surface

The optical reflection from the Si(100) 2 × 1 surface has been calculated, using the discrete dipole model and local polarizabilities obtained from quantum mechanical cluster calculations. Results have been compared with experimental differential reflectance (Si) and optical anisotropy measurements (Ge).

Surface disorder production during plasma immersion implantation

Comparative investigations were performed using high-depth-resolution Rutherford backscattering (RBS) combined with channeling, spectroellipsometry (SE) and atomic force microscopy (AFM) to analyze surface disorder and surface roughness formed during plasma immersion implantation of silicon (100) substrates in a gas mixture containing PH3. In order to enhance the sensitivity to the determination of the oxygen content of the surface oxide layer, the 3.05 MeV (4He+, 4He+) nuclear resonance was used in combination with channeling. For the analysis of SE data we used the method in which an appropriate optical model is assumed and a best fit to the model parameters is obtained (i.e. the thickness of surface oxide and damaged silicon layers and the volume fraction of the components). Evaluation of RBS spectra yields damage profiles consistent with those obtained by SE modelling.

Broad spectrum optical phase retarder using three metallic mirrors for normal and Brewster's angle of incidence ellipsometry

An optical phase retarder for the photon energy range of 1.5–5.5 eV (825–225 nm) is described. The use of metallic mirrors yields good transmission in the entire energy range and the smooth energy dependence of the phase shift is convenient for in situ spectroscopic ellipsometric applications. The optical properties of the retarder are in good agreement with its expected values. The retarder has proved to be a valuable improvement in ellipsometry measurements and enables the use of a conventional rotating polariser ellipsometer for normal incidence measurements.

Optical anisotropy of Ge(001)

The surface induced optical anisotropy in the electronic structure of clean Ge(001) 2×1 was studied with an ellipsometer at normal incidence. The change in the reflection difference between light polarized parallel and perpendicular to the dimer bond at this surface upon either absorption of molecular oxygen or Ar+ ion bombardment was recorded. Both procedures were found to give the same results. It was possible to obtain a qualitative agreement of the optical spectrum recorded and the position and parity of the occupied and unoccupied surface states known on the clean surface.