Critical point energy as a function of electric field determined by electroreflectance of surface-intrinsic-n(+) type doped GaAs

Abstract

Electroreflectance of surface-intrinsic-n(+) type doped GaAs has been measured over a various biased voltage. The spectra have exhibited many Franz-Keldysh oscillations (FKOs) above band gap energy E-g. The electric field F and critical point energy E-c can be determined from the slope and intercept of FKOs fitting. Hence, we can obtain E-c as a function of F. In most of previous works, E-c is taken as E-g. However, it was found that E-c increases with F in this work. In order to explain this, the gain of energy of electron and hole in F was discussed. (C) 2004 American Institute of Physics.