Optical properties of indium phosphide in the 50-200 Å wavelength region using a reflectivity technique

The optical constants of indium phosphide (InP) in the soft x-ray region of 50-200 angstrom are determined from angle-dependent reflectivity measurements. The measurements are carried out using the reflectivity beam line at the Indus-1 synchrotron source. The derived optical constants are compared with tabulated values of Henke et al. [At. Data Nucl. Data Tables 54, 181 (1993)]. Experimental values of delta and beta are in close agreement with the tabulated values in the lower wavelength region of 50-120 angstrom. The experimental value indicates an edge shift of 0.4 angstrom toward the lower wavelength side from the phosphorous L-edge value of 92 angstrom. However, above the 120 angstrom region, where the indium N-2 edge falls at 160.7 angstrom, there is a huge difference between experimental and tabulated values. Both delta and beta values are significantly higher. In contrast to tabulated values of the beta/delta d ratio, which is more than 1 above the 140 angstrom region, the experimental measured ratio is found to be less than 1. This study presents the first reported experimental values of optical constants for InP in this wavelength range, to the best of our knowledge. (C) 2010 Optical Society of America