STRUCTURE, CHEMISTRY, AND BAND BENDING AT SE-PASSIVATED GAAS(001) SURFACES

Se-passivated n-GaAs(001) surfaces prepared in a metalorganic chemical vapor desposition reactor have been investigated by means of x-ray photoelectron spectroscopy, low-energy electron diffraction, and x-ray photoelectron diffraction. The band bending of these free surfaces was as low as ∼0.1 eV, indicating excellent passivation. It was found that Se undergoes an anion exchange reaction with As to depths of at least five atomic layers. This result suggests that the reduction of surface states is brought about by the formation of a GaAsxSe1-x/GaAs heterojunction interface of very high structural quality.