INSITU PHOTOREFLECTANCE STUDY OF SCHOTTKY-BARRIER FORMATION IN INP(110)

The effects of using different p-InP (110) surfaces (air exposed, metal covered, and annealed) on the surface Fermi level position are studied by photoreflectance (PR). Measurements are performed on the (110) atomical clean surface under ultrahigh vacuum conditions in a molecular beam epitaxy chamber. The built-in electric field, which is associated with the barrier height, at the surface and/or metal/InP interface is evaluated from the Franz-Keldysh oscillations exhibited in the PR spectra. Schottky barrier heights of 0.21 +/- 0.02 eV for an atomically clean surface, 0.47 +/- 0.03 eV for an air exposed surface and 0.82 +/- 0.05 eV for a surface annealed at 350-degrees-C are found. In addition, the Schottky barrier height for the Ag/p-InP(110) and Au/InP(110) interfaces are found to be almost identical (0.43 +/- 0.04 and 0.47 +/- 0.03 eV, respectively), while for A1/p-InP(110) the barrier height is 0.60 +/- 0.04 eV. Due to the low doping level and possibly thin metal coverage, our values of the barrier height are less than previous photoemission studies.