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Browsing Research Centers by Author "Abak, M. K."

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    Nanoscale charging hysteresis measurement by multifrequency electrostatic force spectroscopy, insulating substrates, silicon nanocrystals
    (American Institute of Physics, 2008-03-04) Bostanci, U.; Abak, M. K.; Aktas, O.; Dana, A.
    We report a scanning probe technique that can be used to measure charging of localized states on conducting or partially insulating substrates at room temperature under ambient conditions. Electrostatic interactions in the presence of a charged particle between the tip and the sample is monitored by the second order flexural mode, while the fundamental mode is used for stabilizing the tip-sample separation. Cycling the bias voltage between two limits, it is possible to observe hysteresis of the second order mode amplitude due to charging. Results are presented on silicon nitride films containing silicon nanocrystals.
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    Parametrically coupled multiharmonic force imaging
    (AIP Publishing, 2008) Abak, M. K.; Aktas, O.; Mammadov R.; Gürsel, I.; Dâna, A.
    We report use of nonlinear tip-sample interactions to parametrically convert the frequency components of periodic tip-sample interaction forces to frequencies where they can be resonantly detected. One flexural mode of a cantilever is used for tapping-mode imaging and another flexural mode is used for detection of forces converted in presence of an externally injected mechanical oscillation at the difference frequency of the detecting mode and a harmonic of the tapping mode. Material contrast in attractive and repulsive regimes are demonstrated on samples with polymethyl methacrylate patterns and with deoxyribonucleic acid strands on silicon. © 2008 American Institute of Physics.