Photoemission study of chemisorption and Fermi-level pinning at K/GaAs(1 0 0) interface with synchrotron radiation

• Published in: Applied surface science 2005-08, Vol.249 (1), p.340-345
• Main Authors: Sun, M.H., Zhao, T.X., Jia, C.Y., Xu, P.S., Lu, E.D., Hsu, C.C., Ji, Hang
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; Fermi-level pinning; Photoemission and photoelectron spectra; Physics; Schottky barrier; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); X-ray photoelectron spectroscopy
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2004.12.012

The adsorption of K on the n-GaAs(1 0 0) surface was investigated by X-ray photoelectron spectroscopy (XPS) and synchrotron radiation photoemission spectroscopy (SR–PES). The Ga3d and As3d core level was measured for clean and K adsorbed GaAs(1 0 0) surface. The adsorption of K induced chemical reaction between K and As, and the K–As reactant formed when the K coverage θ > 1 ML. The chemical reaction between K and Ga did not occur, but Ga atoms were exchanged by K atoms. From the data of band bending, the Schottky barrier is 0.70 eV. The Fermi-level pinning was not caused by defect levels. The probable reason is that the dangling bonds of surface Ga atoms were filled by the outer-shell electrons of K atoms, forming a half-filled surface state. The Fermi-level pinning was caused by this half-filled surface state.