Optical Properties of CuInSe2 Bulk Material Characterized by a Fixed Polarizer-Rotating Analyzer Spectroscopic Ellipsometer

Abstract

In the present paper, we have investigated the optical properties of CuInSe2 single and polycrystals using a broad band fixed polarizer–rotating analyzer spectroscopic ellipsometer (RAE) in the spectral range 250 to 1700 nm. The wavelength dependence of CuInSe2 optical constants was studied assuming a two-phase system: the ambient medium and the sample. We have determined interband transition energies near and above the bandgap by a detailed analysis of the absorption spectrum and through the third joint-density-of-states (JDOS) derivative computation. Measurements were carried out on nearly-stoichiometric and In-rich CuInSe2 substrates.