Field inhomogeneity effects on photoreflectance spectra of ZnSe/GaAs

Photoreflectance measurements from ZnSe epilayers of different thicknesses were carried out. In photoreflectance spectra, the exciton line shape "rota tion" is observed to be much slower than that in the reflectance spectra by increasing the epilayer thicknesses. To analyze the exciton line shape rot ation quantitatively, the photoreflectance spectra were calculated consider ing the built-in electric field inhomogeneity effects near the interface as well as the interference effects. Calculated line shapes of the photorefle ctance spectra show a good agreement with the observations. Our results imp ly that inhomogeneity effects of the interface built-in electric field play s an important role in the spectral rotation in photoreflectance. (C) 2000 American Institute of Physics. [S0021-8979(00)06208-3].