THE USE OF HIGH-RESOLUTION ELECTRON-ENERGY-LOSS SPECTROSCOPY FOR REFINING THE INFRARED OPTICAL-CONSTANTS OF GAS, GASE, AND INSE

Cleaved surfaces of III-VI lamellar semiconducting compounds GaS, GaSe , and InSe have been studied by high resolution electron-energy-loss s pectroscopy (HREELS). The infrared optical constants of the materials were retrieved by using the dielectric theory taking account of the re sonance frequencies published from infrared reflectivity (IRS) data. T he limitations of the HREELS and IRS measurements in the case of these materials are discussed in detail. However, it is shown that, by comb ining the informations from both spectroscopies, it is possible to ref ine some of the oscillator strengths of these materials.