EFFECT OF CHEMICAL TREATMENT ON THE PHOTOREFLECTANCE OF SEMIINSULATING GAAS

The influence of chemical etching on the photoreflectance (PR) spectra of semi-insulating (SI) GaAs has been investigated. Different PR spec tra were obtained after chemical treatment in alkaline and acid soluti ons, respectively. Different chemical compositions on the sample surfa ce were measured. An oxide film was formed only on the surface of the sample etched in an alkaline solution. The role of the film interferen ce effect in the PR spectra is discussed. Details of the chemical proc esses of etching are given, and the surface polarization conditions ar e discussed.