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Author Xu, Q. ♦ Hsu, J. W.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ GALLIUM ARSENIDES ♦ GERMANIUM ♦ MICROSCOPY ♦ CRYSTAL DEFECTS ♦ THIN FILMS ♦ ELECTROSTATICS ♦ INTERFACES ♦ SURFACE POTENTIAL ♦ FERMI LEVEL ♦ CAPACITANCE
Abstract We apply electrostatic force microscopy (EFM) to study defects in GaAs films grown on Ge. On a GaAs film with surface antiphase boundaries (APBs), we reproducibly measure the surface contact potential (SCP) at the APBs to be (30{plus_minus}5) mV higher than that of the domains, due to the surface Fermi level at APBs being pinned closer to the valence band maximum. On a thick film which contains buried APBs and wedge-shaped depressions on the surface, we find that the SCP of the wedge-shaped depressions is (25{plus_minus}5) mV lower than that of the GaAs surface. Hence, these wedge-shaped depressions have defect electronic states different from those of APBs. The capacitance gradient ({partial_derivative}C/{partial_derivative}z) contrasts on the two samples are also shown to arise from different origins. Factors that can affect the measured SCP and {partial_derivative}C/{partial_derivative}z values are discussed. We demonstrate a new application of EFM to distinguish different types of defects by measuring variations in relative SCP (thus the work function or position of Fermi level) and/or {partial_derivative}C/{partial_derivative}z on sample surfaces. The spatial resolutions of SCP and {partial_derivative}C/{partial_derivative}z are 30 nm, limited by the tip size. {copyright} {ital 1999 American Institute of Physics.}
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 1999-03-01
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 85
Issue Number 5


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