Electrostatic force microscopy studies of surface defects on GaAs/Ge films
- Department of Physics, University of Virginia, Charlottesville, Virginia 22901 (United States)
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.}
- OSTI ID:
- 321459
- Journal Information:
- Journal of Applied Physics, Vol. 85, Issue 5; Other Information: PBD: Mar 1999
- Country of Publication:
- United States
- Language:
- English
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