Fluctuation Microscopy Studies of Medium-range Order Structures in Amorphous Tetrahedral Semiconductors

2000 ◽  
Vol 638 ◽  
Author(s):  
Xidong Chen ◽  
J. Murray Gibson ◽  
John Sullivan ◽  
Tom Friedmann ◽  
Paul Voyles
Keyword(s):  
Thermal Annealing ◽  
Random Network ◽  
Carbon Films ◽  
Range Order ◽  
Diamond Like Carbon ◽  
Medium Range Order ◽  
Microscopy Technique ◽  
Medium Range ◽  
Annealing Effects ◽  
Fluctuation Microscopy

AbstractWe applied fluctuation microscopy technique to study medium-range order in tetrahedral semiconductor materials, such as amorphous silicon, amorphous diamond-like carbon films. It is shown that this technique is very sensitive to local structure changes in the medium range order and promises solutions to open questions that cannot be answered by current techniques. For asdeposited amorphous germanium and silicon, we previously identified a fine-grain para-crystallite structure [1, 2], which will be relaxed into a lower-energy continuous random network structure after thermal annealing. With the same fluctuation microscopy technique, we however found that thermal annealing introduces medium-range order in amorphous diamond-like carbon films. Future studies will be focused on modeling and systematic exploration of annealing effects.

Short and Medium Range Order in Hydrogenated Diamond-Like Carbon Films

2007 ◽  
Vol 13 (S02) ◽  
Author(s):  
A Liu ◽  
R Arenal ◽  
X Chen ◽  
D Miller ◽  
A Erdemir ◽  
...  
Keyword(s):  
Carbon Films ◽  
Range Order ◽  
Diamond Like Carbon ◽  
Medium Range Order ◽  
Medium Range

scholarly journals Fluctuation Microscopy Studies Of Aluminum Oxides Exposed To CL Ions

2002 ◽  
Vol 738 ◽  
Author(s):  
Xidong Chen ◽  
John Sullivan ◽  
Charles Barbour ◽  
Craig Johnson ◽  
Guangwen Zhou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Aluminum Oxide ◽  
Amorphous Material ◽  
Range Order ◽  
Aluminum Oxides ◽  
Medium Range Order ◽  
Microscopy Technique ◽  
Medium Range ◽  
Fluctuation Microscopy ◽  
Physical Changes

ABSTRACTFluctuation electron microscopy studies have been performed on several aluminum oxides exposed to different electrochemical conditions. Little is known about amorphous aluminum oxide structures and their relationship with their passivation behaviors. Corrosion studies have shown that exposure of aluminum oxide films to Cl ions in solution reduces the oxide's passivity, and this results in the onset of pitting corrosion. The physical changes that occur in the oxide as a result of Cl exposure have not been previously identified due to the difficulty in investigating the structure of this amorphous material. Fluctuation microscopy is a new electron microscopy technique that is able to detect the presence of medium range order structures in amorphous systems. In this paper, we will report fluctuation microscopy results on amorphous aluminum oxides that have been exposed to Cl ions in solution and compare them with oxides that have seen no electrolyte exposure or that have been exposed to electrolytes that do not contain Cl-,such as SO42- containing electrolytes. We will also compare the Cl-exposed oxides with oxides that have been implanted with Cl ions. The differences in pitting behaviors for these oxidesare consistent with our previous speculation on the effect of medium range order on the passivation behavior of aluminum oxides grown using ozone.

Medium-Range Order Structures of Amorphous Diamond-Like Carbon Films

2001 ◽  
Vol 675 ◽  
Author(s):  
Xidong Chen ◽  
J. Murray Gibson ◽  
John Sullivan ◽  
Tom Friedmann
Keyword(s):  
Correlation Function ◽  
Density Functional ◽  
Dark Field ◽  
Carbon Films ◽  
Range Order ◽  
Diamond Like Carbon ◽  
Medium Range Order ◽  
Medium Range ◽  
Order Structures ◽  
Body Correlation

ABSTRACTIn this paper, we have studied medium-range order structures in amorphous diamond-like carbon films with fluctuation microscopy. Medium-range order structures are quantified by a specific form of a general four-body correlation. We name this function as a pair-pair alignment correlation function. By analyzing speckle dark-field images taken over different areas as a function of momentum transfer in reciprocal space, we measured the pair-pair alignment correlation function for both thermally annealed samples and unannealed samples. We have found that thermal annealing introduces medium-range order in amorphous diamond-like carbon films, causing more pairs of atoms to be aligned. These results agree with density-functional simulations. Larger-scale simulations will be needed to fully understand our experimental results.

Fluctuation Microscopy Studies of Medium-range Order Structures of Near Frictionless Carbon Films

2004 ◽  
Vol 10 (S02) ◽  
pp. 798-799
Author(s):  
Xidong Chen ◽  
Jacqueline Johnson ◽  
Jon Hiller ◽  
Zhongyi Liu
Keyword(s):  
Carbon Films ◽  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Microscopy ◽  
Order Structures

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Stress relaxation and medium-range order in diamond-like amorphous carbon films

2004 ◽  
Vol 839 ◽  
Author(s):  
Xidong Chen ◽  
John Sullivan ◽  
Tom Friedmann ◽  
Dean Miller
Keyword(s):  
Stress Relaxation ◽  
Great Increase ◽  
Carbon Films ◽  
Range Order ◽  
Diamond Like Carbon ◽  
Medium Range Order ◽  
Amorphous Carbon Films ◽  
Medium Range ◽  
The Relationship ◽  
Order Structures

ABSTRACTIn this paper, we have studied the relationship between medium-range order structures in and stress relaxation in amorphous diamond-like carbon films with fluctuation microscopy. Our preliminary results show strong correlation between stress relaxation and medium-range order. Our previous results showed that annealing films that had been through stress relaxation procedures caused great increase of medium-ranger order. In this paper, we have found that the increase of medium-range order in films that have been annealed before going through stress relaxation through removal of substrates is less pronounced than that of films that have been annealed after removal of substrates. We will discuss interpretations and implications of these results.

The Structure of Ion-Implanted Amorphous Silicon

1998 ◽  
Vol 540 ◽  
Author(s):  
J. M. Gibson ◽  
J-Y. Cheng ◽  
P. Voyles ◽  
M.M.J. TREACY ◽  
D.C. Jacobson
Keyword(s):  
Amorphous Silicon ◽  
Network Model ◽  
Random Network ◽  
Amorphous Semiconductors ◽  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Large Heat ◽  
Continuous Random Network ◽  
Ion Implanted

AbstractUsing fluctuation microscopy, we show that ion-implanted amorphous silicon has more medium-range order than is expected from the continuous random network model. From our previous work on evaporated and sputtered amorphous silicon, we conclude that the structure is paracrystalline, i.e. it possesses crystalline-like order which decays with distance from any point. The observation might pose an explanation for the large heat of relaxation that is evolved by ion-implanted amorphous semiconductors.

Fluctuation Microscopy in the STEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 226-227
Author(s):  
P. M. Voyles ◽  
D. A. Muller
Keyword(s):  
Random Network ◽  
Dark Field ◽  
Distribution Functions ◽  
Disordered Materials ◽  
Microscopy Technique ◽  
Medium Range ◽  
Fluctuation Microscopy ◽  
Image Position ◽  
Continuous Random Network ◽  
Vector Magnitude

Fluctuation microscopy is an electron microscopy technique sensitive to medium-range order (MRO) in disordered materials. It has been applied to study amorphous germanium and silicon, leading to the conclusion that these materials exhibit more MRO than the conventional continuous random network model for their structure.As originally proposed by Treacy and Gibson, fluctuation microscopy utilizes mesoscopicresolution (1.5 nm) hollow-cone dark field (HCDF) imaging in a TEM. The normalized variance of such images,is a measure of the magnitude of fluctuations in the diffracted intensity from mesoscopic volumes of the sample and is sensitive to MRO via the three- and four-body atom distribution functions. Studying V as a function of the diffraction vector magnitude k gives information about the degree of MRO and the internal structure of ordered regions. V as a function of the inverse resolution Q gives information about the characteristic MRO length scale.

scholarly journals Fluctuation Microscopy: What is it?

2005 ◽  
Vol 13 (5) ◽  
pp. 20-21 ◽  
Author(s):  
Michael M. J. Treacy
Keyword(s):  
Amorphous Materials ◽  
Range Order ◽  
Disordered Materials ◽  
Atomic Ordering ◽  
Thin Sample ◽  
Length Scales ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Microscopy

Fluctuation microscopy is the enigmatic name given to an otherwise straightforward technique for studying medium range order in highly disordered materials. By medium range, we mean atomic ordering at length scales within the range 0.5-2.0 nm, where traditional imaging and diffraction techniques have the most difficulty detecting structural correlations in amorphous materials. Puzzlement over fluctuation microscopy generally arises not because of the "microscopy" part of the name, but because of the "fluctuation" part. What, exactly, is fluctuating? And, why does it fluctuate?The fluctuations are simply the variations in scattering between small sub-volumes within a thin sample. These are usually not timevarying fluctuations (although they could be), but instead they are the position-varying fluctuations in local diffraction.

Fluctuation microscopy: a probe of medium range order

2005 ◽  
Vol 68 (12) ◽  
pp. 2899-2944 ◽  
Author(s):  
M M J Treacy ◽  
J M Gibson ◽  
L Fan ◽  
D J Paterson ◽  
I McNulty
Keyword(s):  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Microscopy
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