Study of Schottky barrier formation in InP [110] by photoreflectance

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] atomic 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+or-0.02 eV for an atomically clean surface, 0.47+or-0.03 eV for an air exposed surface, and 0.82+or-0.05 eV for a surface annealed at 350 degrees C are found. In addition, the Schottky barrier heights for the Ag/p-InP[110] and Au/InP [(110] interfaces are found to be almost identical (0.43+or-0.04 eV and 0.47+or-0.03 eV, respectively), while for Al/p-InP[110] the barrier height is 0.60+or-0.04 eV. >