On the Effect of Local Barrier Height in Scanning Tunneling Microscopy: Measurement Methods and Control Implications

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dc.contributor.ORCID0000-0002-6135-1993 (Tajaddodianfar, F)en_US
dc.contributor.authorTajaddodianfar, Fariden_US
dc.contributor.authorMoheimani, S. O. Rezaen_US
dc.contributor.authorOwen, J.en_US
dc.contributor.authorRandall, J. N.en_US
dc.contributor.utdAuthorTajaddodianfar, Fariden_US
dc.contributor.utdAuthorMoheimani, S. O. Rezaen_US
dc.date.accessioned2018-10-24T22:48:45Z
dc.date.available2018-10-24T22:48:45Z
dc.date.created2018-01-02en_US
dc.date.issued2018-10-24
dc.description.abstractA common cause of tip-sample crashes in a Scanning Tunneling Microscope (STM) operating in constant current mode is the poor performance of its feedback control system. We show that there is a direct link between the Local Barrier Height (LBH) and robustness of the feedback control loop. A method known as the "gap modulation method" was proposed in the early STM studies for estimating the LBH. We show that the obtained measurements are affected by controller parameters and propose an alternative method which we prove to produce LBH measurements independent of the controller dynamics. We use the obtained LBH estimation to continuously update the gains of a STM proportional-integral (PI) controller and show that while tuning the PI gains, the closed-loop system tolerates larger variations of LBH without experiencing instability. We report experimental results, conducted on two STM scanners, to establish the efficiency of the proposed PI tuning approach. Improved feedback stability is believed to help in avoiding the tip/sample crash in STMs.en_US
dc.description.departmentErik Jonsson School of Engineering and Computer Scienceen_US
dc.description.sponsorshipAir Force Research Laboratory Contract No. FA8650-15-C-7542.en_US
dc.identifier.bibliographicCitationTajaddodianfar, F., S. O. Reza Moheimani, J. Owen, and J. N. Randall. 2018. "On the effect of local barrier height in scanning tunneling microscopy: Measurement methods and control implications." Review of Scientific Instruments 89(1), doi:10.1063/1.5003851en_US
dc.identifier.issn0034-6748en_US
dc.identifier.issue1en_US
dc.identifier.urihttp://hdl.handle.net/10735.1/6250
dc.identifier.volume89en_US
dc.language.isoenen_US
dc.publisherAmerican Institute of Physics Incen_US
dc.relation.urihttp://dx.doi.org/10.1063/1.5003851en_US
dc.rights©2017 The Authorsen_US
dc.source.journalReview of Scientific Instrumentsen_US
dc.subjectAdaptive control systemsen_US
dc.subjectFeedback control systemsen_US
dc.subjectScanning tunneling microscopyen_US
dc.subjectElectric power supply, Constant-currenten_US
dc.subjectFeedback control systemsen_US
dc.subjectFeedback control systems--Stabilityen_US
dc.subjectMeasurementen_US
dc.subjectPID controllersen_US
dc.titleOn the Effect of Local Barrier Height in Scanning Tunneling Microscopy: Measurement Methods and Control Implicationsen_US
dc.type.genrearticleen_US

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