Abstract
Surface electronic structures of n-GaP(001) and p-InP(001) with and without sulfur treatment have been studied by X-ray photoelectron spectroscopy (XPS), synchrotron radiation photoemission spectroscopy (SRPES), and inverse photoemission spectroscopy (IPES). The Fermi level (EF) of a clean n-GaP(001)-(2x4) surface is found to be pinned at 0.2 eV above the valence band maximum (VBM), suggesting that the surface electronic bands are bent upward. XPS spectra reveal that the EF is moved to 2.3 eV above the VBM by the sulfur treatment, implying that the sulfur-treated surface has flat bands. The IPES result shows that empty dangling bond states on Ga atoms at the surface are located at the conduction band minimum (CBM) and they disappeared with the treatment. SRPES spectra of a clean p-InP(001)-(2x4) surface indicate that the EF is located at 0.3 eV above the VBM and surface states due to phosphorus atoms are at –0.9 eV below the EF. The result implies that the surface has almost flat bands. Empty dangling bond states on In atoms at the clean surface are found to be located at the conduction band edge. Surface states due to the In-S bonds are found at –3.5 eV below the EF for the sulfur-treated surface. The sulfur treatment of the clean surface leads to a little shift (0.1 –0.2 eV) of the EF and to considerable reduction of the empty states in the band gap. A type conversion of p- to n- is not observed in the present work. This is discussed in terms of the thickness of a sulfide layer.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.