Electroreflectance of surface-intrinsic- n+-type doped GaAs

Measurements of the electroreflectance spectra of surface-intrinsic- n+-type-doped GaAs at various bias voltages (Vbias) were conducted. Findings indicate many Franz-Keldysh oscillations (FKOs) above the band-gap energy which were attributed to a uniform electric field (F) in the undoped layer below the surface. No other evidence for the uniformity of F in the undoped layer was observed. Since F can be deduced from the periods of the FKOs, the relations between Vbias an F can be obtained. Thus, the relation confirms the existence of a nearly uniform field in the undoped layer.