Optical constants of silicon and silicon dioxide using soft X-ray reflectance measurements

Abstract

Using the synchrotron radiation source Indus-1, we have performed the angle dependent reflectance measurements in the soft X-ray region, on etched silicon (1 1 1) wafer and silicon dioxide wafer. The data so obtained is used to evaluate the optical constants ` δ' and ` β' in the wavelength region 80–200 Å for the two materials. The results are compared with the tabulated data of Henke et al. and other reported experimental results. It has been found that the data for silicon is in close agreement with the tabulated data away from the silicon L absorption edge with significant deviations near the edge. The experimentally obtained β values for silicon dioxide are consistent with the Henke's tabulated data where as the δ values show an upward trend with a shift of 9% from the tabulated values.The experimental data is also compared with energy dependent measurements done by Filatova et al. on non crystalline silicon dioxide and it is found that our data although match closely with that of Filatova's below 140 Å, but after 140 Å, Filatova's values for δ show a downward trend while our data follow the same upward trend as the tabulated values of Henke et al.