Gs. Chang et al., Determination of surface state density for GaAs and InAlAs by room temperature photoreflectance, J APPL PHYS, 86(3), 1999, pp. 1765-1767
Room temperature photoreflectance (PR) was used to investigate the surface
state densities of GaAs and In0.52Al0.48As surface intrinsic-n(+) structure
s. The built-in electric field and thus the surface barrier height are eval
uated using the observed Franz-Keldysh oscillations in the PR spectra. Base
d on the thermionic emission theory and current-transport theory, the surfa
ce state density as well as the pinning position of the Fermi level can be
determined from the dependence of the surface barrier height on the pump be
am intensity. Even though this method is significantly simpler, easier to p
erform, and time efficient compared with other approaches, the results obta
ined agree with the literature. (C) 1999 American Institute of Physics. [S0
021-8979(99)03815-3].