Scanning tunneling microscopy of polymers: A status report

Scanning tunneling microscopy (STM) has evolved rapidly in the past few years. Major developments have occurred in instrumentation, theory, and in a wide range of applications. In this paper, an overview of the application of STM and related techniques to polymers will be given, followed by a discussion of current research issues and prospects for future developments. The application of STM to polymers can be conveniently divided into the following subject areas: atomic scale imaging of uncoated polymer structures; topographic imaging and metrology of man-made polymer structures; and modification of polymer structures. Since many polymers are poor electrical conductors and hence unsuitable for use as a tunneling electrode, the related atomic force microscopy (AFM) technique which is capable of imaging both conductors and insulators has also been applied to polymers.The STM is well known for its high resolution capabilities in the x, y and z axes (Å in x andy and sub-Å in z). In addition to high resolution capabilities, the STM technique provides true three dimensional information in the constant current mode. In this mode, the STM tip is held at a fixed tunneling current (and a fixed bias voltage) and hence a fixed height above the sample surface while scanning across the sample surface.

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Imaging Semiconductors, Metals and Molecules with Scanning Tunneling Microscopy

Australian Journal of Physics ◽

10.1071/ph900393 ◽

1990 ◽

Vol 43 (5) ◽

pp. 393 ◽

Cited By ~ 3

Author(s):

RJ Wilson ◽

S Chiang ◽

DD Chambliss

Keyword(s):

High Resolution ◽

Scanning Tunneling Microscopy ◽

Scale Structure ◽

Atomic Scale ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Aromatic Molecules ◽

Metal On Metal ◽

High Resolution Images ◽

Insight Into

A brief review of applications of scanning tunneling microscopy (STM) to studies of clean and adsorbate covered surfaces is given. For metal-semiconductor systems, high resolution images provide insight into nucleation phenomena and atomic scale structure. For the metal on metal systems of Ag and Ni on Au(l11) we report surprising new nucleation phenomena. Finally, we show that images of flat lying aromatic molecules can be obtained.

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Imaging The Atomic-Scale Structure of Molybdenum and Vanadium Oxides by Scanning Tunneling Microscopy

MRS Proceedings ◽

10.1557/proc-332-507 ◽

1994 ◽

Vol 332 ◽

Author(s):

Gregory S. Rohrer ◽

Weier Lu ◽

Richard L. Smith

Keyword(s):

Scanning Tunneling Microscopy ◽

Chemical Vapor ◽

Shear Plane ◽

Structural Features ◽

Atomic Scale ◽

Constant Current ◽

Chemical Vapor Transport ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Coordination Polyhedra

ABSTRACTSingle crystals of Na0.003V2O5 and Mo18O52 were grown by chemical vapor transport and cleaved surfaces were imaged in ultrahigh vacuum using scanning tunneling microscopy (STM). Because the Mo18O52 (100) and Na0.003V2O5 (010) surfaces of these layered materials have a bulk terminated structure, the atomic-scale contrast in constant current images can be directly compared to components of the bulk structure. Among the structural features identified in the STM images are the surface/crystallographic shear plane intersections, the different MoOx coordination polyhedra on the Mo18O52 (100) surface, and the VO5 square pyramids that make up the Na0.003V2O5 (010) surface. In each of these cases, it was found that the atoms closest to the tip dominate the image contrast.

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Practical applications of scanning tunneling microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152069 ◽

1989 ◽

Vol 47 ◽

pp. 18-19

Author(s):

D. R. Denley

Keyword(s):

High Resolution ◽

Scanning Tunneling Microscopy ◽

Quantitative Information ◽

Digital Data ◽

Scanning Tunneling ◽

Ambient Atmosphere ◽

Tunneling Microscopy ◽

Clear Trend ◽

Practical Applications ◽

Promising Tool

Scanning tunneling microscopy (STM) has recently been introduced as a promising tool for analyzing surface atomic structure. We have used STM for its extremely high resolution (especially the direction normal to surfaces) and its ability for imaging in ambient atmosphere. We have examined surfaces of metals, semiconductors, and molecules deposited on these materials to achieve atomic resolution in favorable cases.When the high resolution capability is coupled with digital data acquisition, it is simple to get quantitative information on surface texture. This is illustrated for the measurement of surface roughness of evaporated gold films as a function of deposition temperature and annealing time in Figure 1. These results show a clear trend for which the roughness, as well as the experimental deviance of the roughness is found to be minimal for evaporation at 300°C. It is also possible to contrast different measures of roughness.

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Scanning Tunneling Microscopy of Amorphous Carbon Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180343 ◽

1990 ◽

Vol 48 (1) ◽

pp. 318-319

Author(s):

Mircea Fotino ◽

D.C. Parks

Keyword(s):

Scanning Tunneling Microscopy ◽

Amorphous Carbon ◽

Carbon Films ◽

Atomic Scale ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Amorphous Carbon Films ◽

Image Optimization ◽

Step Procedure ◽

Stm Images

In the last few years scanning tunneling microscopy (STM) has made it possible and easily accessible to visualize surfaces of conducting specimens at the atomic scale. Such performance allows the detailed characterization of surface morphology in an increasing spectrum of applications in a wide variety of fields. Because the basic imaging process in STM differs fundamentally from its equivalent in other well-established microscopies, good understanding of the imaging mechanism in STM enables one to grasp the correct information content in STM images. It thus appears appropriate to explore by STM the structure of amorphous carbon films because they are used in many applications, in particular in the investigation of delicate biological specimens that may be altered through the preparation procedures.All STM images in the present study were obtained with the commercial instrument Nanoscope II (Digital Instruments, Inc., Santa Barbara, California). Since the importance of the scanning tip for image optimization and artifact reduction cannot be sufficiently emphasized, as stressed by early analyses of STM image formation, great attention has been directed toward adopting the most satisfactory tip geometry. The tips used here consisted either of mechanically sheared Pt/Ir wire (90:10, 0.010" diameter) or of etched W wire (0.030" diameter). The latter were eventually preferred after a two-step procedure for etching in NaOH was found to produce routinely tips with one or more short whiskers that are essentially rigid, uniform and sharp (Fig. 1) . Under these circumstances, atomic-resolution images of cleaved highly-ordered pyro-lytic graphite (HOPG) were reproducibly and readily attained as a standard criterion for easily recognizable and satisfactory performance (Fig. 2).

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