Novel contactless mode of electroreflectance

We report a new contactless mode of electroreflectance which utilizes a condenserlike system. One electrode consists of a transparent conductive coating on a transparent substrate which is separated from the sample surface by a thin layer of air. We have measured the contactless electroreflectance spectra at 300 K from a number of materials including semi-insulating bulk GaAs, bulk narrow gap Hg0.8Cd0.2Te, a GaAs structure with a large, uniform electric field and a GaAs/Ga1−xAlxAs (x≊0.2) coupled double quantum well.