NOVEL CONTACTLESS ELECTROREFLECTANCE SPECTROSCOPY OF SEMICONDUCTORS

Optical reflectance difference technique has been applied to semiconductors. It has been demonstrated that differential reflectance spectroscopy (DR) can be equivalent to contactless electromodulation. The measured DR spectra of GaAs are comparable to the published electroreflectance data and show marked improvement in the signal-to-noise ratio over the photoreflectance spectra of the same samples. We have used this method to study the confined energy levels in InGaAs/GaAs multiple quantum wells and have found good agreement with the theoretically predicted values. We conclude that DR is a viable alternative to photoreflectance as a contactless electromodulation technique.