A Study of the Surface Morphological Features of the Polar Faces of ZnO by Atomic Force Microscopy (AFM) Methods and AlN Thin Films Deposited on ZnO Polar Faces by PLD

1996 ◽  
Vol 449 ◽  
Author(s):  
M. J. Suscavage ◽  
D. F. Ryder ◽  
P. W. Yip
Keyword(s):  
Atomic Force Microscopy ◽  
High Vacuum ◽  
Interface Reaction ◽  
Morphological Features ◽  
Laser Evaporation ◽  
Atmospheric Conditions ◽  
Reaction Products ◽  
Force Microscopy ◽  
Atomic Force ◽  
Thermally Processed

ABSTRACTThe effects of both temperature and atmosphere on the resulting morphological features of the polar faces of single crystal ZnO were investigated and characterized by atomic force microscopy (AFM). In studies where ZnO was thermally processed in flowing oxygen at atmospheric conditions within the temperature range of 500°C to 900°C for 30 minutes, the Znsurface (i.e., (000 1)) showed a tendency to reconstruct with increasing temperature until terraces became evident at 900°C. Terrace heights were as small as 0.9 nm. In contrast, the O-surface (i.e., (000 ī)) was observe to change very little during the O2-atmoshere, thermal treatment and remained comparatively rougher than the Zn-surface. ZnO samples which were thermally processed under high vacuum (i.e., 5 × 10-7 Torr) conditions exhibited a more dramatic contrast. The vacuum annealed Zn-surface was observed to develop very smooth surface features (Roughness = 0.09 nm) at annealing temperatures within the 700 – 800°C range. In contrast, and as expected, the O-surface roughness increased due to surface reduction reactions. In addition to these findings, it is noted that AFM measurements may be utilized as a convenient method to distinguish between the two polar surfaces of ZnO.Aluminum nitride was deposited on the Zn- and O- surfaces from 700 to 850°C by pulsed laser evaporation. X-ray diffraction indicated that the AIN was c-axis oriented with no interface reaction products detected between the ZnO substrate and AIN film.

Bonding Force Investigation between C-S-H Clusters in the C3S Pastes and AFM Tip

2011 ◽  
Vol 250-253 ◽  
pp. 630-635
Author(s):  
Hai Yan Sun ◽  
Ai Min Gong ◽  
Yu Lin Peng
Keyword(s):  
Atomic Force Microscopy ◽  
Normal Distribution ◽  
Experimental Method ◽  
Mechanical Characteristic ◽  
Structural Model ◽  
Atmospheric Conditions ◽  
Bonding Force ◽  
Force Microscopy ◽  
Solid Ratio ◽  
Atomic Force

With the experimental objects of the C3S pastes curing at 60 days with water-solid ratio of 0.5, the micro mechanical characteristic between C-S-H clusters and tip has been investigated in the low scale. The results show that the experimental method is feasible for bonding force between C-S-H clusters and tip using atomic force microscopy (AFM) in the real atmospheric conditions. Though bonding force values are discrete in view of the anisotropy character of the cement-based material, the normal distribution can be fitted for the variation of bonding force between C-S-H blusters in the C3S pastes and AFM tip with a mean of 6.2nN. Even if bonding force values is somewhat higher due to the roughness and the measuring conditions in the paper, the experimental method using AFM could still be effective for the lateral correlation for bonding force of the different systems. The research on bonding force between C-S-H clusters would play the important role in establishing the new microscopic structural model.

Development of a Self-Excited Oscillator for SI-Traceable Measurements in Atomic Force Microscopy

2008 ◽  
Author(s):  
Gregory W. Vogl ◽  
Jon R. Pratt
Keyword(s):  
Atomic Force Microscopy ◽  
International System ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Transducers ◽  
Analog Control ◽  
System Of Units ◽  
Excited Oscillator

A new self-excited micro-oscillator is proposed as a velocity reference that could aid the dissemination of nanonewton-level forces that are traceable to the International System of Units (SI). An analog control system is developed to keep the actuation side of the device oscillating sinusoidally with an amplitude that is fairly insensitive to the quality factor. Consequently, the device can be calibrated as a velocity reference in air and used in ultra-high vacuum with a velocity shift of less than one percent. Hence, the calibrated micro-oscillator could be used with electrostatic forces to calibrate cantilevers used for atomic force microscopy (AFM) as SI-traceable force transducers. Furthermore, the calibrated micro-oscillator could potentially be used as an AFM sensor to achieve atomic resolutions on par with those realized in frequency-modulation AFM (FM-AFM) with quartz tuning forks.

Atomic-Force Microscopy with piezoresistive cantilevers

1994 ◽  
Vol 52 ◽  
pp. 1064-1065
Author(s):  
M. Tortonese ◽  
F. J. Giessibl
Keyword(s):  
Atomic Force Microscopy ◽  
Electron Tunneling ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Cantilever Deflection ◽  
Force Microscopy ◽  
Large Samples ◽  
Atomic Force ◽  
High Lateral Resolution ◽  
Piezoresistive Cantilevers

The atomic force microscope (AFM) works by measuring the deflection of a cantilever as it is scanned over a sample. A sharp tip at the end of the cantilever is responsible for the high lateral resolution achieved with the AFM. There are several ways to measure the deflection of the cantilever. The technique used to measure the deflection of the cantilever most often dictates the mechanical complexity and stability of the instrument. Electron tunneling, interferometry and capacitive sensors have been used successfully. The most common way to measure the cantilever deflection is by means of an optical deflection detector.The piezoresistivc cantilever offers a new way to measure the deflection of the cantilever, with performances comparable to the performances of other deflection detectors, and with the advantage that the sensor is incorporated in the cantilever. This simplifies the design and operation of the microscope In particular, the piezoresistive cantilever facilitates the use and often improves the performances of an AFM when operated in ultra high vacuum (UHV), at low temperature, or when used to image large samples.

The study of the formation of nanocomposite thin-walled fluoroplastic coatings on metal substrates of various nature using atomic force microscopy

2020 ◽  
pp. 41-56
Author(s):  
I. A. Makarova ◽  
A. V. Filonovich ◽  
V.N. Gadalov ◽  
E.A. Filatov
Keyword(s):  
Atomic Force Microscopy ◽  
Thin Layer ◽  
Morphological Features ◽  
Thin Wall ◽  
Metal Substrates ◽  
Force Microscopy ◽  
Composite Systems ◽  
Atomic Force ◽  
Thin Walled ◽  
Disperse Nanoparticles

The paper presents the results of the research on the formation of nanocomposite fluoroplastic thin-wall coatings on substrates: 45 steel; copper and Al, formed under various conditions using the method of atomic force microscopy. Morphological features of the nanophase thin-layer fluoroplastic coatings with disperse nanoparticles have been studied. A model for the formation of nanophase composite systems is proposed.

scholarly journals Effect of the tip state during qPlus noncontact atomic force microscopy of Si(100) at 5 K: Probing the probe

2012 ◽  
Vol 3 ◽  
pp. 25-32 ◽  
Author(s):  
Adam Sweetman ◽  
Sam Jarvis ◽  
Rosanna Danza ◽  
Philip Moriarty
Keyword(s):  
Atomic Force Microscopy ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Dissipated Energy ◽  
Tunnel Current ◽  
Force Microscopy ◽  
Atomic Force ◽  
Wide Range ◽  
Characteristic Imaging

Background: Noncontact atomic force microscopy (NC-AFM) now regularly produces atomic-resolution images on a wide range of surfaces, and has demonstrated the capability for atomic manipulation solely using chemical forces. Nonetheless, the role of the tip apex in both imaging and manipulation remains poorly understood and is an active area of research both experimentally and theoretically. Recent work employing specially functionalised tips has provided additional impetus to elucidating the role of the tip apex in the observed contrast. Results: We present an analysis of the influence of the tip apex during imaging of the Si(100) substrate in ultra-high vacuum (UHV) at 5 K using a qPlus sensor for noncontact atomic force microscopy (NC-AFM). Data demonstrating stable imaging with a range of tip apexes, each with a characteristic imaging signature, have been acquired. By imaging at close to zero applied bias we eliminate the influence of tunnel current on the force between tip and surface, and also the tunnel-current-induced excitation of silicon dimers, which is a key issue in scanning probe studies of Si(100). Conclusion: A wide range of novel imaging mechanisms are demonstrated on the Si(100) surface, which can only be explained by variations in the precise structural configuration at the apex of the tip. Such images provide a valuable resource for theoreticians working on the development of realistic tip structures for NC-AFM simulations. Force spectroscopy measurements show that the tip termination critically affects both the short-range force and dissipated energy.

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