Reflection Anistropy Spectroscopy Study of the Near Surface Electric Field in Low-Temperature Grown GaAs (001)

We have evaluated an ‘‘effective depletion width’’ of =\u3c 45 Å and the sign (n-type/upward band bending) of the near surface electric field in low-temperature grown GaAs ~001! using the optical method of reflection anisotropy spectroscopy in the vicinity of the spin-orbit split E1 , E1 + Delta1 optical features. Our results provide evidence that surface Fermi level pinning occurs for air exposed (001) surfaces of undoped low temperature grown GaAs