Thermal and chemical stability of Se‐passivated GaAs surfaces

We report on the thermal and chemical stability of (100) GaAs interfaces passivated with aqueous, selenium‐based reagents. Photoluminescence from the Se treated surfaces shows that they remain passivated after extended water rinses. The surfaces were studied under ultrahigh vacuum by reflection high‐energy electron diffraction (RHEED) from room temperature to 620 °C. A streaky (1×1) RHEED pattern at low temperature gives way at 580 °C to a stable (4×1) reconstruction, suggesting strong bonding between Se and the GaAs surface. X‐ray photoelectron spectroscopy confirms the presence of Se at the surface at high temperature, possibly in the form of gallium selenate. The stability of these Se‐treated interfaces suggests that chemical treatments could be used in conjunction with molecular beam epitaxy to obtain high‐quality regrown interfaces.