Electroreflectance and surface photovoltage spectroscopies of semiconductor structures using an indium-tin-oxide-coated glass electrode in soft contact mode

Measurements of electroreflectance and surface photovoltage spectroscopy of semiconductor structures are described using a transparent indium-tin-oxide-coated glass electrode in soft contact mode on the semiconductor surface. This improvisation (simplification) reduces the magnitude of the ac modulation voltage necessary for the electroreflectance measurement to less than a volt from about a kV (similar to 10(3) V) as required in the conventional contactless setup. This soft contact mode also enhances the sensitivity of the surface photovoltage signal by three orders of magnitude. We also formulate an analytical criterion to extract the transition energies of a quantum well from the surface photovoltage spectrum. (C) 2001 American Institute of Physics.