Combining Scanning Probe Microscopy and Transmission Electron Microscopy

Nafari, Alexandra; Angenete, Johan; Svensson, Krister; Sanz‐Velasco, Anke; Olin, Håkan

doi:10.1007/978-3-642-10497-8_3

Cited by 4 publications

(3 citation statements)

References 151 publications

(193 reference statements)

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“…A way to monitor most of the parameters directly is to do the experiment using an STM inside a transmission electron microscope (TEM) where one can image the tip-surface system while manipulating it [33] , [34] . All important parameters are accessible by TEM imaging: the tip-surface distance, tip radius, movement of tip or sample material, while the STM provide tip motion and bias voltage.…”

Section: Resultsmentioning

confidence: 99%

Surface Modifications by Field Induced Diffusion

2012

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By applying a voltage pulse to a scanning tunneling microscope tip the surface under the tip will be modified. We have in this paper taken a closer look at the model of electric field induced surface diffusion of adatoms including the van der Waals force as a contribution in formations of a mound on a surface. The dipole moment of an adatom is the sum of the surface induced dipole moment (which is constant) and the dipole moment due to electric field polarisation which depends on the strength and polarity of the electric field. The electric field is analytically modelled by a point charge over an infinite conducting flat surface. From this we calculate the force that cause adatoms to migrate. The calculated force is small for voltage used, typical 1 pN, but due to thermal vibration adatoms are hopping on the surface and even a small net force can be significant in the drift of adatoms. In this way we obtain a novel formula for a polarity dependent threshold voltage for mound formation on the surface for positive tip. Knowing the voltage of the pulse we then can calculate the radius of the formed mound. A threshold electric field for mound formation of about 2 V/nm is calculated. In addition, we found that van der Waals force is of importance for shorter distances and its contribution to the radial force on the adatoms has to be considered for distances smaller than 1.5 nm for commonly used voltages.

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Section: Resultsmentioning

confidence: 99%

Surface Modifications by Field Induced Diffusion

2012

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“…The microscope is mainly used to obtain structural information while the SPM instruments are used to perform the material analysis by applying forces or electrical currents [1]. The space available inside SEM instruments is comparatively large and several probes can be used [2].…”

Section: Introductionmentioning

confidence: 99%

“…The space available inside SEM instruments is comparatively large and several probes can be used [2]. In TEM the space is much more limited and usually only one SPM probe is fitted [1], while two probes have also recently been demonstrated [3]. One major drawback with the SEM is that the resolution is limited by the electron-probe shape and the imaging mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Image formation mechanisms in scanning electron microscopy of carbon nanotubes, and retrieval of their intrinsic dimensions

2013

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Image formation mechanisms in scanning electron microscopy of carbon nanotubes,and retrieval of their intrinsic dimensions.. , 124: 35-39 Access to the published version may require subscription. N.B. When citing this work, cite the original published paper. Ultramicroscopy Permanent link to this version:http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-16425Image formation mechanisms in scanning electron microscopy of carbon nanotubes, and retrieval of their intrinsic dimensions. AbstractWe present a detailed analysis of the image formation mechanisms that are involved in the imaging of carbon nanotubes with scanning electron microscopy (SEM). We show how SEM images can be modelled by accounting for surface enhancement effects together with the absorption coefficient for secondary electrons, and the electron-probe shape. Images can then be deconvoluted, enabling retrieval of the intrinsic nanotube dimensions. Accurate estimates of their dimensions can thereby be obtained even for structures that are comparable to the electron-probe size (on the order of 2 nm). We also present a simple and robust model for obtaining the outer diameter of nanotubes without any detailed knowledge about the electron-probe shape.

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