Controlled surface fermi-level on the SeS_2-Passivated n-GaAs(100)

摘要

Selenium disulfide surface treatment can unpin the surface Fermi-level on n-GaAs (100) surfaces, resulting in a reduction in the surface band bending. The long-term stability of the surface Fermi-level unpinning has been studied using photoreflectance spectroscopy under room ambient conditions. Our results show that the SeS_2-treated n-GaAs(100) surface is stable up to four months with negligible shift in the surface Fermi-level being noted. The mechanism of the long-term stability is attributed to the layered surface structure formed on the SeS_2-treated n-GaAs(100) surface. The chemical structure of the passivated surface was determined by synchrotron radiation phtoemission spectroscopy. The outermost layer of sulfur and arsenicbased sulfides and selenides may protect the electronic passivating layer, which consists of gallium-based selenides, from interaction with the atmosphere.