On the nature of photoreflectance line shape in GaAs

The photoreflectance (PR) spectra of epitaxial GaAs layers were studied, with emphasis on the sharp ‘‘spike’’ that has been previously observed in the PR spectra of some GaAs samples. By chemically etching the surface of our samples, we were able to separate the ‘‘spike’’ from the rest of the line shape. We conclude that this ‘‘spike’’ is associated with doping inhomogeneities in the samples.