Mechanisms of Fatigue in Polysilicon Mems Structures

2001 ◽  
Vol 687 ◽  
Author(s):  
P. Shrotriya ◽  
S. Allameh ◽  
A. Butterwick ◽  
S. Brown ◽  
W.O. Soboyejo
Keyword(s):  
Perturbation Analysis ◽  
Fatigue Crack Initiation ◽  
Surface Topology ◽  
Linear Perturbation ◽  
Silica Layer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Morphologies ◽  
Surface Silica

AbstractFatigue crack initiation is shown to be associated with the stress-assisted evolution of a surface silica layer that forms during the normal exposure of unpassivated polysilicon surfaces to lab air In-situ atomic force microscopy (AFM) techniques are used to reveal the evolution of overall surface topology during incremental cyclic deformation to failure. Linear perturbation analysis of stress-assisted dissolution is then utilized to predict the evolution of the surface morphology. The predictions from the perturbation analysis are shown to be consistent with measured surface morphologies obtained using AFM techniques.

On the Evolution of Surface Morphology of Polysilicon Mems Structures During Fatigue

2000 ◽  
Vol 657 ◽  
Author(s):  
S. M. Allameh ◽  
B. Gally ◽  
S. Brown ◽  
W.O. Soboyejo
Keyword(s):  
Atomic Force Microscopy ◽  
Room Temperature ◽  
Surface Topology ◽  
Ex Situ ◽  
Surface Processes ◽  
Chemical Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Large Wavelength

ABSTRACTThis paper presents the results of an atomic force microscopy (AFM) study of the evolution of surface topology in notched polysilicon MEMS structures deformed under cyclic loading at room temperature. The in-situ and ex-situ AFM studies reveal changes in surface topology after cyclic actuation at a relative humidity of ∼70%. These lead ultimately to large wavelength modulations close to the bottom of the notch, in the areas where the tensile stresses are maximum. This is in contrast with the wavelength of the surface modulations away from the notch, which remain relatively unchanged. The results are discussed in terms of possible chemical/surface processes that can occur in the presence of water vapor.

Investigation of the Temperature-Dependent Surface Morphology of p-Sexiphenyl Thin Films on KCl(001)

2001 ◽  
Vol 708 ◽  
Author(s):  
E.J. Kintzel ◽  
E.S. Gillman ◽  
J.G. Skofronick ◽  
S.A. Safron ◽  
D.-M. Smilgies
Keyword(s):  
Thin Film ◽  
Surface Morphology ◽  
Vapor Deposition ◽  
Vacuum Chamber ◽  
Base Pressure ◽  
Temperature Dependent ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Morphologies

ABSTRACTInvestigation into the temperature dependence of the surface morphology of a thin film of p-sexiphenyl (p-6P) on KCl(001) was carried out by atomic force microscopy (AFM). An individual p-6P film was prepared by vapor deposition at a base pressure of ∼1x10-8 mbar onto a KCl(001) surface which was maintained at 323 K during deposition. The AFM was carried out in a separate vacuum chamber, in situ, at a base pressure of ∼1x10-6 mbar. The p-6P film was cooled and maintained at discrete temperatures in the range from 294 K to 128 K as AFM measurements were performed. Similar surface morphologies are observed for film temperatures maintained at 294, 264, and 227 K, and 188 and 128 K during the AFM measurements. AFM images for the first set of film temperatures (294 - 227 K) indicate the presence of block-like islands of p-6P, with well-defined crystallite boundaries. AFM images of the films in the second set (188 and 128 K) indicate the presence of triangular wedge-shaped structures of p-6P preferentially aligned nearly in the direction of the [110]KCl. Comparison of these wedge-shaped structures at the indicated film temperatures reveals they are rotated by approximately 180° with respect to each other. Subsequent images of the surface of the p-6P film captured again at 294 K, after the final 128 K temperature study was completed, revealed the same surface features found for the initial 294 K film temperature.

scholarly journals Ultrafine metal-polymer catalysts based on polyconjugated systems for Fisher–Tropsch synthesis

2020 ◽  
Vol 92 (6) ◽  
pp. 977-984
Author(s):  
Mayya V. Kulikova ◽  
Albert B. Kulikov ◽  
Alexey E. Kuz’min ◽  
Anton L. Maximov
Keyword(s):  
Tropsch Synthesis ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
Force Microscopy ◽  
Composite Catalysts ◽  
Fe Catalyst ◽  
Atomic Force ◽  
And Function ◽  
Metal Polymer

AbstractFor previously studied Fischer–Tropsch nanosized Fe catalyst slurries, polymer compounds with or without polyconjugating structures are used as precursors to form the catalyst nanomatrix in situ, and several catalytic experiments and X-ray diffraction and atomic force microscopy measurements are performed. The important and different roles of the paraffin molecules in the slurry medium in the formation and function of composite catalysts with the two types of aforementioned polymer matrices are revealed. In the case of the polyconjugated polymers, the alkanes in the medium are “weakly” coordinated with the metal-polymer composites, which does not affect the effectiveness of the polyconjugated polymers. Otherwise, alkane molecules form a “tight” surface layer around the composite particles, which create transport complications for the reagents and products of Fischer-Tropsch synthesis and, in some cases, can change the course of the in situ catalyst formation.

Atomic force microscopy of in situ deformed nickel thin films

1999 ◽  
Vol 353 (1-2) ◽  
pp. 194-200 ◽  
Author(s):  
C. Coupeau ◽  
J.F. Naud ◽  
F. Cleymand ◽  
P. Goudeau ◽  
J. Grilhé
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Force Microscopy ◽  
Nickel Thin Films ◽  
Atomic Force

scholarly journals Degradation Mechanism of Porous Metal-Organic Frameworks by In Situ Atomic Force Microscopy

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 722
Author(s):  
Ioanna Christodoulou ◽  
Tom Bourguignon ◽  
Xue Li ◽  
Gilles Patriarche ◽  
Christian Serre ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Degradation Mechanism ◽  
Metal Organic Frameworks ◽  
Porous Metal ◽  
Force Microscopy ◽  
Atomic Force ◽  
Metal Organic ◽  
The Media ◽  
Ph Conditions

In recent years, Metal-Organic Frameworks (MOFs) have attracted a growing interest for biomedical applications. The design of MOFs should take into consideration the subtle balance between stability and biodegradability. However, only few studies have focused on the MOFs’ stability in physiological media and their degradation mechanism. Here, we investigate the degradation of mesoporous iron (III) carboxylate MOFs, which are among the most employed MOFs for drug delivery, by a set of complementary methods. In situ AFM allowed monitoring with nanoscale resolution the morphological, dimensional, and mechanical properties of a series of MOFs in phosphate buffer saline and in real time. Depending on the synthetic route, the external surface presented either well-defined crystalline planes or initial defects, which influenced the degradation mechanism of the particles. Moreover, MOF stability was investigated under different pH conditions, from acidic to neutral. Interestingly, despite pronounced erosion, especially at neutral pH, the dimensions of the crystals were unchanged. It was revealed that the external surfaces of MOF crystals rapidly respond to in situ changes of the composition of the media they are in contact with. These observations are of a crucial importance for the design of nanosized MOFs for drug delivery applications.

In Situ Characterization of the Mechanical Behavior of Gecko's Spatulae by Atomic Force Microscopy

2013 ◽  
Vol 22 ◽  
pp. 85-93
Author(s):  
Shuang Yi Liu ◽  
Min Min Tang ◽  
Ai Kah Soh ◽  
Liang Hong
Keyword(s):  
Mechanical Behavior ◽  
Hierarchical Level ◽  
Intrinsic Properties ◽  
In Situ Characterization ◽  
Force Microscopy ◽  
Atomic Force ◽  
Theoretical Predictions ◽  
Multi Mode

In-situ characterization of the mechanical behavior of geckos spatula has been carried out in detail using multi-mode AFM system. Combining successful application of a novel AFM mode, i.e. Harmonix microscopy, the more detail elastic properties of spatula is brought to light. The results obtained show the variation of the mechanical properties on the hierarchical level of a seta, even for the different locations, pad and stalk of the spatula. A model, which has been validated using the existing experimental data and phenomena as well as theoretical predictions for geckos adhesion, crawling and self-cleaning of spatulae, is proposed in this paper. Through contrast of adhesive and craw ability of the gecko on the surfaces with different surface roughness, and measurement of the surface adhesive behaviors of Teflon, the most effective adhesion of the gecko is more dependent on the intrinsic properties of the surface which is adhered.

Use of in-situ atomic force microscopy to monitor the biodegradation of polyhydroxyalkanoates (PHAs)

2001 ◽  
Vol 167 (1) ◽  
pp. 139-151 ◽  
Author(s):  
Connie J. Rossini ◽  
Justinn F. Arceo ◽  
Evan R. McCarney ◽  
Brian H. Augustine ◽  
Douglas E. Dennis ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force
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