Wavelength Modulated Reflectivities of the Direct Exciton Edge in GaP

Abstract

The wavelength derivative spectra of the direct exciton edge were observed in the temperature range from 80 to 300 K. The structures due to direct excitons were clearly observed and the accurate dependence of exciton energies on temperature was obtained. Line shape analysis was also made by using the Wannier exciton function as well as the model exciton dielectric function introduced first by Hopfield and Thomas. It was shown that the exciton dead layer plays an important role in optical reflectance of the direct edge.