Published online by Cambridge University Press: 21 February 2011
A new technique for obtaining the electroreflectance (ER) spectrum, Vacuum Electroreflectance (VER), is introduced. In VER, the modulating electric field is applied capacitively using a transparent electrode as one plate and the sample as the other plate, with vacuum in between. In this geometry, cooling or heating is achieved without any sample preparation. Precise positioning is achieved by piezoelectric motors monitored by a HeNe interferometer, and cooling to 80 K by the Joule-Thompson effect. GaAs samples with different Si doping are used to compare VER to Electrolyte ER and Photoreflectance.