Cover Page. The handle holds various files of this Leiden University dissertation.

Transcription

1 Cover Page The handle holds various files of this Leiden University dissertation. Author: Tabak, F.C. Title: Towards high-speed scanning tunneling microscopy Issue Date:

2 Towards high-speed scanning tunneling microscopy

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4 Towards high-speed scanning tunneling microscopy PROEFSCHRIFT ter verkrijging van de graad van Doctor aan de Universiteit Leiden, op gezag van Rector Magnificus prof. mr. C.J.J.M. Stolker, volgens besluit van het College voor Promoties te verdedigen op woensdag 5 juni klokke 13:45 uur door Femke Chantal Tabak geboren te Hilversum in 1984

5 Promotiecommissie Promotor: Co-promotor: Overige leden: Prof. dr. J. W. M. Frenken Dr. ir. W.M. van Spengen (Technische Universiteit Delft) Prof. dr. E. R. Eliel Prof. dr. U. Staufer (Technische Universiteit Delft) Prof. dr. P. Rudolf (Rijksuniversiteit Groningen) Prof. dr. ir. T. H. Oosterkamp Prof. dr. J. Aarts Dr. F. Galli Prof. dr. ing. A. J. H. M. Rijnders (Universiteit Twente) Casimir PhD series, Delft-Leiden ISBN An electronic version of this thesis can be found at and at The work described in this thesis was performed at the Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, The Netherlands and the Department of Precision - and Microsystems Engineering, Delft University of Technology, The Netherlands. It was financially supported by a Netherlands SmartMix grant and the nimic partner organisations.

6 Contents 1 STM and the need for faster scanners STM principle Need for Speed: the importance of fast scanners Current state-of-the-art fast scanners Summary Target MEMS-based STM scanners MEMS introduction Working principle Failure modes of MEMS devices Fabrication Introduction to MEMS STM scanners Advantages of MEMS in STM systems Resonance frequencies MEMS-piezo hybrid scanning system State-of-the-art high-speed MEMS SPM Implementation of MEMS STM scanners Design criteria of MEMS scanners Finite-element based MEMS scanner design MEMS actuation tested by AFM and white-light interferometry Tip growth on MEMS Tip requirements Deposition techniques Platinum STM tips by EBID Conductance measurements of EBID tips Towards atomic resolution High-speed MEMS scanner actuation and capacitive coupling Mechanical integration of a MEMS scanner Summary v

7 Contents 4 Design of a high-speed STM with exchangeable scanning element Design considerations Scanner design The scanner body and approach mechanism Sample holder High-speed scan configurations UHV system and eddy current damping Summary MEMS STM experiments First tunneling experiments MEMS-based STM on Au(111) Conclusions on MEMS STM scanners Recommendations Tip deposition Incorporation in an STM Compensation of force and torque in piezo-based STM scanners Z-direction: force compensation Electronic testing of the z-direction piezo elements Mechanical characterisiation Out-of-plane force balancing: conclusion In-plane actuation: force or torque? Electronic characterisation Mechanical characterisation Force and torque compensation: conclusion Image distortions in high-speed imaging Introduction Scanner characterisation with STM data Fourier analysis The role of the actuation signal shape Appearance of higher harmonics in the linescan signal Image linearization after sinusoidal scanning Frequency modulation during sinusoidal scanning Influence of signal shape on image quality Pro s and Con s of a compensating piezo element Response to actuation of the compensating x piezo element vi

8 Contents Response to actuation of the compensating y piezo element Compensation: conclusion High-speed scanning Conclusions A Two- and three-dimensional MEMS scanners 143 Bibliography 145 Summary 157 Samenvatting 161 Curriculum Vitae 165 List of Publications 167 vii

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