Semiconductor core-level to valence-band maximum binding-energy differences: precise determination by X-ray photoelectron spectroscopy

• Published in: Physical review. B, Condensed matter Condensed matter, 1983-01, Vol.28 (4), p.1965-1977
• Main Authors: KRAUT, E. A, GRANT, R. W, WALDROP, J. R, KOWALCZYK, S. P
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; Photoemission and photoelectron spectra; Physics
• ISSN: 0163-1829; 1095-3795
• DOI: 10.1103/PhysRevB.28.1965

Angle-resolved core-level and valence-band X-ray photoelectron spectroscopy (XPS) data for GaAs(110), Ge(110) and Ge(111) surfaces are analyzed to determine core-level to valence-band max. binding-energy differences to a precision of the order of the room-temp. thermal energy. A method for markedly improving the precision with which the position of the valence-band max. in XPS data can be located is presented. This method is based on modeling the XPS valence-band spectrum in the vicinity of the valence-band max. by an instrumentally broadened theoretical valence-band density-of-states and fitting this model to the experimental data using the least-squares method. The factors which influence the attainable precision for determining core-level to valence-band max. binding-energy differences are quantitatively discussed. These factors include the presence of occupied surface states, band bending, surface chemical shifts, background effects associated with inelastic processes, instrumental line shape and spectrometer calibration accuracy. Ths spin-orbit--split components of the Ga, arsenic and Ge 3d core lines are resolved and binding energies of these components, measured relative to the valence-band max. in GaAs and Ge, are reported. 55 ref.--AA