ELECTROREFLECTANCE OF SURFACE-INTRINSIC-N(-TYPE DOPED GAAS())

The electroreflectance spectra of surface-intrinsic-n(+)-type-doped Ga As were measured at various bias voltages (V-bias). Results revealed m any Franz-Keldysh oscillations (FKOs) above the band-gap energy, which have been attributed to a uniform electric field (F) in the undoped l ayer below the surface. However, there has been no other evidence for the uniformity of F in the undoped layer. Since it is known that F can be deduced from the periods of the FKOs, the relations between F and V-bias can, thereby, be obtained. The nearly linear relation, thus fou nd, confirms the existence of a nearly uniform field in the undoped la yer. From the plot of F against V-bias,the Values of the thickness of the undoped layer and the barrier height can also be evaluated. (C) 19 97 American Institute of Physics.