OPTICAL SPECTROSCOPY OF EPITAXIAL GA2SE3 LAYERS FROM THE FAR-INFRAREDTO THE ULTRAVIOLET

Epitaxial Ga2Se3 layers were grown on GaP (100) and GaAs (100) by meta l-organic chemical vapor deposition and the heterovalent exchange reac tion, respectively. Measurements of the sample reflectance were carrie d out in the spectral range from 70 to 50 000 cm(-1) (similar to 10 me V -6.2 eV). The dielectric functions in the ar infrared were determine d from the reflectance measurements and are dominated by strong phonon features of the substrate and the layers. Substrate related multiphon on absorbances and Fabry-Perot interference dominate the mid infrared range. The spectra in the visible spectral range reveal Fabry-Perot in terferences up to 2.6 eV indicating a fundamental band gap energy in t he blue spectral range in contrast to the previously reported lower va lue of 2 eV. Further electronic transition energies were observed at 3 .9 4.7, and 5.0 eV. (C) 1996 American Institute of Physics.