Development of a 3D Tunneling Current Probing System for Micro- and Nano-Coordinate Metrology

2017 ◽  
Vol 870 ◽  
pp. 126-131
Author(s):  
Zhong Yuan Sun ◽  
Alexander Schuler ◽  
Tino Hausotte
Keyword(s):  
Position Control ◽  
Three Dimensional ◽  
Tunneling Current ◽  
Free Form ◽  
Scanning Tunneling ◽  
Work Piece ◽  
Large Area ◽  
Tunneling Microscopy ◽  
Positioning Systems ◽  
Coordinate Metrology

The demands for precision measurement of three dimensional micro-and nanogeometries over a large area have rapidly increased during the last few years. To meet such requirements, many different nanometre resolving 3D capable probing sensors and corresponding 3D positioning systems to operate the sensors for 3D measurements have been developed. The mechanical contact-free, electrical work piece probing based on the scanning tunneling microscopy principle offers new possibilities for 3D micro coordinate measurements as well as for nanometre resolved topography measurements in micro-and nanometrology. This paper introduces an updated version of this probing sensor system extended with a 3D movable piezo scanner to directly detect its probing direction. With the magnitude and the direction of the contact vector forwarded to the position control of the nanopositioning and nanomeasuring machine NMM-1 all of the 3D measurement commands of NMM-1 can be utilized, allowing 3D surface scans and especially 3D free-form surface scans.

Study of Tip-Surface Interactions in Scanning Tunneling Microscopy (STM) by Reflection Electron Microscopy (REM)

1990 ◽  
Vol 48 (1) ◽  
pp. 320-321
Author(s):  
W. Lo ◽  
J.C.H. Spence ◽  
M. Kuwabara
Keyword(s):  
High Resolution ◽  
Elastic Strain ◽  
Tunneling Current ◽  
Surface Damage ◽  
Surface Interactions ◽  
Graphite Surface ◽  
Scanning Tunneling ◽  
Large Area ◽  
Tunneling Microscopy ◽  
High Resolution Tem

Work on the integration of STM with REM has demonstrated the usefulness of this combination. The STM has been designed to replace the side entry holder of a commercial Philips 400T TEM. It allows simultaneous REM imaging of the tip/sample region of the STM (see fig. 1). The REM technique offers nigh sensitivity to strain (<10−4) through diffraction contrast and high resolution (<lnm) along the unforeshortened direction. It is an ideal technique to use for studying tip/surface interactions in STM.The elastic strain associated with tunnelling was first imaged on cleaved, highly doped (S doped, 5 × 1018cm-3) InP(110). The tip and surface damage observed provided strong evidence that the strain was caused by tip/surface contact, most likely through an insulating adsorbate layer. This is consistent with the picture that tunnelling in air, liquid or ordinary vacuum (such as in a TEM) occurs through a layer of contamination. The tip, under servo control, must compress the insulating contamination layer in order to get close enough to the sample to tunnel. The contaminant thereby transmits the stress to the sample. Elastic strain while tunnelling from graphite has been detected by others, but never directly imaged before. Recent results using the STM/REM combination has yielded the first direct evidence of strain while tunnelling from graphite. Figure 2 shows a graphite surface elastically strained by the STM tip while tunnelling (It=3nA, Vtip=−20mV). Video images of other graphite surfaces show a reversible strain feature following the tip as it is scanned. The elastic strain field is sometimes seen to extend hundreds of nanometers from the tip. Also commonly observed while tunnelling from graphite is an increase in the RHEED intensity of the scanned region (see fig.3). Debris is seen on the tip and along the left edges of the brightened scan region of figure 4, suggesting that tip abrasion of the surface has occurred. High resolution TEM images of other tips show what appear to be attached graphite flakes. The removal of contamination, possibly along with the top few layers of graphite, seems a likely explanation for the observed increase in RHEED reflectivity. These results are not inconsistent with the “sliding planes” model of tunnelling on graphite“. Here, it was proposed that the force due to the tunnelling probe acts over a large area, causing shear of the graphite planes when the tip is scanned. The tunneling current is then modulated as the planes of graphite slide in and out of registry. The possiblity of true vacuum tunnelling from the cleaned graphite surface has not been ruled out. STM work function measurements are needed to test this.

A comparative STM and TEM study of polycarbonate substrates

1987 ◽  
Vol 45 ◽  
pp. 438-439
Author(s):  
R. Reifenberger ◽  
A. M. Baro ◽  
L. Vazquez ◽  
A. Bartolami ◽  
N. Garcia ◽  
...  
Keyword(s):  
Electron Tunneling ◽  
Three Dimensional ◽  
Tunneling Current ◽  
Sample Surface ◽  
Real Space ◽  
Scanning Tunneling ◽  
Vertical Position ◽  
Exponential Dependence ◽  
Tunneling Microscopy ◽  
Wide Range

Scanning tunneling microscopy (STM) is the newest method that allows real space imaging of surfaces on a scale extending to atomic dimensions. The STM technique was developed by C. Binnig, H. Rohrer, and co-workers at IBM Zurich laboratories and is notable for its ability to image a wide range of materials under a variety of different conditions. The technique has received considerable attention for its ability to provide information about postions of individual surface atoms with unprecendented three-dimensional resolution.The physical basis for the STM is a quantum mechanical electron tunneling from a sharp tip to a conducting substrate. The exponential dependence of the tunneling current with the tip-to-sample separation allows a measurement of vertical position differences smaller than ca. 0.01 nm often with a lateral resolution of better than ca. 0.2 nm. By rastering the tip across a sample surface while monitoring the tunneling current, a three dimensional topographic image of the surface can be obtained.

An Equivalent-Plane Cross-Coupling Position Control for Contour-Accuracy Improvement in Three-Axis Free-Form Contour Following Tasks

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Jian-Wei Ma ◽  
De-Ning Song ◽  
Zhen-Yuan Jia ◽  
Wen-Wen Jiang ◽  
Fu-Ji Wang ◽  
...  
Keyword(s):  
Error Control ◽  
Position Control ◽  
Three Dimensional ◽  
Cross Coupling ◽  
Experimental Tests ◽  
Numerical Control ◽  
Free Form ◽  
Contouring Error ◽  
Contour Following ◽  
Better Than

To reduce the contouring errors in computer-numerical-control (CNC) contour-following tasks, the cross-coupling controller (CCC) is widely researched and used. However, most existing CCCs are well-designed for two-axis contouring and can hardly be generalized to compensate three-axis curved contour following errors. This paper proposes an equivalent-plane CCC scheme so that most of the two-axis CCCs or flexibly designed algorithms can be utilized for equal control of the three-axis contouring errors. An initial-value regeneration-based Newton method is first proposed to compute the foot point from the actual motion position to the desired contour with a high accuracy, so as to establish the equivalent plane where the estimated three-dimensional contouring-error vector is included. After that, the signed contouring error is computed in the equivalent plane, thus a typical two-axis proportional-integral-differential (PID)-based CCC is utilized for its control. Finally, the two-axis control commands generated by the typical CCC are coupled to three-axis control commands according to the geometry of the established equivalent plane. Experimental tests are conducted to verify the effectiveness of the presented method. The testing results illustrate that the proposed equivalent-plane CCC performs much better than conventional method in both error estimation and error control.

scholarly journals Towards Laterally Resolved Ferromagnetic Resonance with Spin-Polarized Scanning Tunneling Microscopy

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 827
Author(s):  
Marie Hervé ◽  
Moritz Peter ◽  
Timofey Balashov ◽  
Wulf Wulfhekel
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Ferromagnetic Resonance ◽  
Tunneling Current ◽  
Magnetic Vortex ◽  
Scanning Tunneling ◽  
Tunneling Junction ◽  
Resonance Signal ◽  
Tunneling Microscopy ◽  
Spin Polarized ◽  
Local Detection

We used a homodyne detection to investigate the gyration of magnetic vortex cores in Fe islands on W(110) with spin-polarized scanning tunneling microscopy at liquid helium temperatures. The technique aims at local detection of the spin precession as a function of frequency using a radio-frequency (rf) modulation of the tunneling bias voltage. The gyration was excited by the resulting spin-polarized rf current in the tunneling junction. A theoretical analysis of different contributions to the frequency-dependent signals expected in this technique is given. These include, besides the ferromagnetic resonance signal, also signals caused by the non-linearity of the I ( U ) characteristics. The vortex gyration was modeled with micromagnetic finite element methods using realistic parameters for the tunneling current, its spin polarization, and the island shape, and simulations were compared with the experimental results. The observed signals are presented and critically analyzed.

Self-Assembled InAs Islands on (AI,Ga)As, an In Situ Scanning Tunneling Microscopy Study

1999 ◽  
Vol 571 ◽  
Author(s):  
P. Ballet ◽  
J.B. Smathers ◽  
G.J. Salamo
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Molecular Beam ◽  
Three Dimensional ◽  
Microscopy Study ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Self Organized ◽  
Scanning Tunneling Microscopy Study ◽  
Island Density

ABSTRACTWe report an in-situ molecular beam epitaxy – scanning tunneling microscopy study of three dimensional (3D) self organized InAs islands on (AI,Ga)As surfaces. The influence of the presence of Al atoms on the roughness of the starting surface and on the island density is shown by investigating several Al compositions. We emphasize the case of InAs/AlAs and point out the major differences between this system and the widely studied InAs/GaAs system.

Relaxation of Nanostructures on the Si(111)(7×7) Surface by High Temperature Scanning Tunneling Microscopy

1998 ◽  
Vol 05 (03n04) ◽  
pp. 821-832 ◽  
Author(s):  
Ayahiko Ichimiya ◽  
Yoriko Tanaka ◽  
Kazuhiko Hayashi
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Three Dimensional ◽  
Thermal Relaxation ◽  
Scanning Tunneling ◽  
Two Dimensional ◽  
Tunneling Microscopy ◽  
Temperature Variable ◽  
Long Lifetime ◽  
Temperature Scanning ◽  
Silicon Islands

Single silicon islands have been produced on the Si(111)(7 × 7) surface by a scanning tunneling microscope (STM) tip. Thermal relaxation of the isolated islands is observed by temperature variable scanning tunneling microscopy with strong tip effects. The sizes of islands depend on time t with a functional form of (t0-t)α. It is found that α≃2/3 for single bilayer islands, and α≃1 for three-dimensional ones. During the decomposition of three-dimensional islands, step bunching of over-layers takes place, while the islands have certain facets, like a pyramid just after the creation. At the final stages of the three-dimensional island decompositions, two-dimensional ones with 5 × 5 structure always appear. We have found that characteristic 5 × 5 islands with a long lifetime are formed during relaxation, but the 7 × 7 islands have mostlt a short lifetime. Rotation of small islands is also observed during relaxation. We discuss the results in terms of two-dimensional vapor phase processes.

The Morphology of Cu Clusters on SrTiO3(001) at Initial Stages of Metal Film Growth

1994 ◽  
Vol 357 ◽  
Author(s):  
Y. Liang ◽  
D. L. Carroll ◽  
D. A. Bonnell
Keyword(s):  
Vapor Deposition ◽  
Metal Film ◽  
Elevated Temperatures ◽  
Film Growth ◽  
Three Dimensional ◽  
Scanning Tunneling ◽  
Low Density ◽  
Tunneling Microscopy ◽  
Defect Sites ◽  
Island Density

AbstractCopper overlayers deposited on nearly stoichiometric SrTiO3(001) have been investigated with scanning tunneling microscopy (STM). Vapor deposition of Cu on a SrTiO3(001) surface at ambient temperature leads to the formation of three dimensional islands (clusters). The distribution of Cu islands appears to be inhomogeneous with two characteristic morphologies. In regions with a low density of Cu islands the Cu was always associated with step edges or defect sites. In regions with a high density of Cu islands the islands exhibit a random but nearly close packed morphology. The variation of Cu island density is indicative of diffusion of Cu clusters on the SrTiO3(001) surface. Diffusion was further confirmed by annealing the Cu/SrTiO3 at elevated temperatures yielding agglomeration of Cu clusters.

ON THE ROLE OF KINKS AND STRAIN IN HETEROEPITAXIAL GROWTH: AN STM STUDY

2000 ◽  
Vol 07 (05n06) ◽  
pp. 673-677
Author(s):  
E. LUNDGREN ◽  
M. SCHMID ◽  
G. LEONARDELLI ◽  
A. HAMMERSCHMID ◽  
B. STANKA ◽  
...  
Keyword(s):  
Diffusion Process ◽  
Scanning Tunneling Microscopy ◽  
Three Dimensional ◽  
Growth Mode ◽  
Scanning Tunneling ◽  
Two Dimensional ◽  
Heteroepitaxial Growth ◽  
Tunneling Microscopy ◽  
Exchange Diffusion

Interlayer diffusion of Co over steps of vacancy islands on the Pt(111) surface as studied by scanning tunneling microscopy is presented. It is demonstrated that Co atoms descend Pt steps by an exchange diffusion process at the step edge with the Pt atoms. Further, the exchange diffusion process is observed to occur at the corners (kinks) of the vacancy islands. The importance of kinks concerning whether the growth mode of a heteropitaxial film is two-dimensional or three-dimensional is demonstrated for the case of thin Co films on Pt(111). We argue that the strain in the Co film is to a large extent responsible for the kink formation.

Growth of Laser Ablated YBa2Cu3O7−δ Films as Examined by Rheed and Scanning Tunneling Microscopy

1992 ◽  
Vol 285 ◽  
Author(s):  
Stephen E. Russek ◽  
Alexana Roshko ◽  
Steven C. Sanders ◽  
David A. Rudman ◽  
J. W. Ekin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Scanning Tunneling Microscopy ◽  
Three Dimensional ◽  
High Energy ◽  
Spiral Growth ◽  
Scanning Tunneling ◽  
Initial Growth ◽  
Rheed Pattern ◽  
Island Growth ◽  
Tunneling Microscopy

ABSTRACTUsing scanning tunneling microscopy (STM) and reflection high energy electron diffraction (RHEED) we have examined the growth morphology, surface structure, and surface degradation of laser ablated YBa2Cu3O7−δ thin films. Films from 5 nm to ltm thick were studied. The films were deposited on MgO and LaAlO3 substrates using two different excimer laser ablation systems. Both island nucleated and spiral growth morphologies were observed depending on the substrate material and deposition rate used. The initial growth mechanism observed for a 5–10 nm thick film is replicated through different growth layers up to thicknesses of 200 run. Beyond 200 rnm, the films show some a-axis grains and other outgrowths. The thinnest films (5–10 nm) show considerable surface roughness on the order of 3–4 nm. For both growth mechanisms the ledge width remains approximately constant (∼ 30 nm) and the surface roughness increases as the film thickness increases. The films with spiral growth have streaked RHEED patterns despite having considerable surface roughness, while the films with island growth have more of a three dimensional diffraction pattern. RHEED patterns were obtained after the film surfaces were degraded by exposure to air, KOH developer, a Br-methanol etch, and a shallow ion mill. Exposure to air and KOH developer caused only moderate degradation of the RHEED pattern whereas a shallow (I nm deep) 300 V ion mill completely destroyed the RHEED pattern.

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