Transition metals on GaAs(110): A case for extrinsic surface states

Journal Article · Tue Jul 01 04:00:00 EDT 1986 · J. Vac. Sci. Technol., B; (United States)

DOI:https://doi.org/10.1116/1.583493· OSTI ID:5661095

Hughes, G; Ludeke, R; Schaeffler, F; Rieger, D

The interactions of transition metal overlayers with the GaAs(110) cleaved surface have been investigated using core level photoemission spectroscopy. The appearance of chemically shifted core level components for coverages of a fraction of a monolayer indicate that both Mn and V overlayers interact strongly with the cleaved surface. At higher coverages there is evidence for the outdiffusion of both Ga and As into the metal overlayer. Valence band spectra for the V overlayer exhibit strong emission in the semiconductor band gap associated with d-italic-electron states of the transition metal atoms. The onset of this emission coincides with the position of the surface Fermi level, which suggests that these states are responsible for Fermi level pinning. Photoemission core level studies suggest that the origin of the interface states is associated with an exchange reaction of the metal and the gallium. The notion that a transition metal impurity state is responsible for the pinning of the Fermi level at the interface is formulated and supported by the experimental results. Fermi level shifts for both n-italic- and p-italic-type crystals were investigated over a broad coverage range. The pinning position in the band gap was found to be identical for both n-italic- and p-italic-type crystals, however the final barrier heights varied for the different transition metals. Schottky barrier heights of 0.75 (0.68) +- 0.05 eV for V and 0.84 (0.59) +- 0.05 eV for Mn were measured for n-italic- and p-italic-type substrates.

• Research Organization: IBM T. J. Watson Research Center, Yorktown Heights, New York 10598
• OSTI ID: 5661095
• Journal Information: J. Vac. Sci. Technol., B; (United States), Journal Name: J. Vac. Sci. Technol., B; (United States) Vol. 4:4; ISSN JVTBD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ARSENIC COMPOUNDS
ARSENIDES
DEPOSITION
DIFFUSION
ELECTRONIC STRUCTURE
ELEMENTS
EMISSION
ENERGY GAP
ENERGY LEVELS
FABRICATION
FERMI LEVEL
GALLIUM
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
MANGANESE
METALS
PHOTOEMISSION
PNICTIDES
POTENTIALS
SCHOTTKY BARRIER DIODES
SECONDARY EMISSION
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SURFACE COATING
TRANSITION ELEMENTS
VALENCE
VANADIUM