Scanning Tunneling Microscopy (Stm) and Scanning Force Microscopy (Sfm) of Liquid Crystals and Polymers

1994 ◽  
Vol 332 ◽  
Author(s):  
K. D. Jandt ◽  
T. J. Mcmaster ◽  
D. G. Mcdonnell ◽  
J. M. Blackmore ◽  
M. J. Miles
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Liquid Crystalline ◽  
Elevated Temperatures ◽  
Crystalline Polymer ◽  
Scanning Force Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Morphological Studies ◽  
Scanning Force

ABSTRACTRecent progress in the field of liquid crystal materials and oriented polymers studied by nearfield scanned probe microscopies (SPM) is presented here. The investigations were focused on scanning tunneling microscopy (STM) results of antiferroelectric liquid crystalline molecules observed at different elevated temperatures corresponding to different bulk mesophases of the material, and on surface morphological studies of a liquid crystalline polymer by scanning force microscopy (SFM). In the field of oriented thermoplastic polymers, SFM images of the morphology and molecular packing in the outermost surface of poly(butene-1) films are presented.

Scanned tip measurement of deep vertical facets on a flat surface: Measuring roughness on gaas laser waveguide mirrors

1993 ◽  
Vol 51 ◽  
pp. 532-533
Author(s):  
Chang Shen ◽  
Phil Fraundorf ◽  
Robert W. Harrick
Keyword(s):  
Integrated Circuits ◽  
Flat Surface ◽  
Scanning Force Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Optoelectronic Integrated Circuits ◽  
Laser Waveguide ◽  
Scanning Force ◽  
Gaas Laser

Monolithic integration of optoelectronic integrated circuits (OEIC) requires high quantity etched laser facets which prevent the developing of more-highly-integrated OEIC's. The causes of facet roughness are not well understood, and improvement of facet quality is hampered by the difficulty in measuring the surface roughness. There are several approaches to examining facet roughness qualitatively, such as scanning force microscopy (SFM), scanning tunneling microscopy (STM) and scanning electron microscopy (SEM). The challenge here is to allow more straightforward monitoring of deep vertical etched facets, without the need to cleave out test samples. In this presentation, we show air based STM and SFM images of vertical dry-etched laser facets, and discuss the image acquisition and roughness measurement processes. Our technique does not require precision cleaving. We use a traditional tip instead of the T shape tip used elsewhere to preventing “shower curtain” profiling of the sidewall. We tilt the sample about 30 to 50 degrees to avoid the curtain effect.

Log-log scale roughness spectroscopy of surfaces

1993 ◽  
Vol 51 ◽  
pp. 224-225
Author(s):  
P. Fraundorf ◽  
B. Armbruster
Keyword(s):  
Power Spectrum ◽  
Autocorrelation Function ◽  
Power Spectra ◽  
Scanning Force Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Scanning Force ◽  
Lateral Structure ◽  
Scale Roughness

Optical interferometry, confocal light microscopy, stereopair scanning electron microscopy, scanning tunneling microscopy, and scanning force microscopy, can produce topographic images of surfaces on size scales reaching from centimeters to Angstroms. Second moment (height variance) statistics of surface topography can be very helpful in quantifying “visually suggested” differences from one surface to the next. The two most common methods for displaying this information are the Fourier power spectrum and its direct space transform, the autocorrelation function or interferogram. Unfortunately, for a surface exhibiting lateral structure over several orders of magnitude in size, both the power spectrum and the autocorrelation function will find most of the information they contain pressed into the plot’s origin. This suggests that we plot power in units of LOG(frequency)≡-LOG(period), but rather than add this logarithmic constraint as another element of abstraction to the analysis of power spectra, we further recommend a shift in paradigm.

Resolution Issues in Scanned Probe Microscopy

1997 ◽  
Vol 3 (S2) ◽  
pp. 1187-1188
Author(s):  
P. E. Russell
Keyword(s):  
Scanning Force Microscopy ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Probe Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sample Height ◽  
Scanned Probe Microscopy ◽  
Scanning Force

Scanned Probe Microscopy first received widespread recognition in the form of scanning tunneling microscopy (STM) images clearly showing atomic resolution of the Si 111 surface in the characteristic 7×7 surface reconstruction. For this sample, STM imaging under carefully controlled ultrahigh vacuum conditions reveals the clear image of each atom position within the surface unit cell with excellent contrast and clearly atomic resolution. Over the past few years, versions of scanning force microscopy (commonly referred to as atomic force microscopy or AFM) have become much more widespread than STM. A very common, and very difficult question, is: What is the resolution of AFM? The simple answer is that SPM in general, and STM and AFM in particular, routinely obtain sub-angstrom resolution—in the z axis, or the sample height direction. This high resolution capability is easily demonstrated by scanning a cleaved crystal of known lattice spacing and observing single and multiple atomic steps.

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