Abstract
Thermal effects in a high vacuum on horizontal Bridgman grown GaAs(001) surface prepared by deoxygenated and de-ionized water treatment were investigated by x-ray photoelectron spectroscopy, low-energy electron diffraction, ultraviolet photoelectron spectroscopy, and photoluminescence (PL) measurement. The ultraviolet photoelectron spectra show that, below 450 °C, the surface Fermi level lies at almost 0.85–1.0 and 0.68–0.8 eV above the valence-band maximum, respectively, for lightly and highly Si-doped GaAs surfaces. Above 480 °C, the surface Fermi levels of both the surfaces gradually come close to 0.45–0.54 eV above the valence-band maximum even though the surface keeps the 2×4 structure. PL measurements suggest that the surface Fermi level position is strongly affected by arsenic and gallium vacancies created near the surface during thermal processing.
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