Abstract
The authors report on photoreflectance (PR) measurements of the electric fields at the surface and GaAs/GaAs interface of doped GaAs films prepared by molecular beam epitaxy (MBE). By using He-Ne and He-Cd lasers alternately as the pump light, PR signals from the surface and interface of the films can be effectively separated because of the difference in the penetration depths of these two pump beams. Electric fields at the surface and interface were evaluated from PR spectra. Film interference effects on modulation spectroscopy have been studied. The origin of the electric field at interfaces has also been discussed.
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