Observations of structural order in ion-implanted amorphous silicon

2001 ◽  
Vol 16 (11) ◽  
pp. 3030-3033 ◽  
Author(s):  
Ju-Yin Cheng ◽  
J. M. Gibson ◽  
D. C. Jacobson
Keyword(s):  
Electron Microscopy ◽  
Amorphous Silicon ◽  
Random Network ◽  
Dark Field ◽  
Range Order ◽  
Length Scale ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Electron Microscopy ◽  
Ion Implanted

Medium-range order in ion-implanted amorphous silicon has been observed using fluctuation electron microscopy. In fluctuation electron microscopy, variance of dark-field image intensity contains the information of high-order atomic correlations, primarily in medium-range order length scale (1–3 nm). Thermal annealing greatly reduces the order and leaves a random network. It appears that the free energy change previously observed on relaxation may therefore be associated with randomization of the network. In this paper, we discuss the origin of the medium-range order during implantation, which can be interpreted as a paracrystalline state, that is, a disordered network enclosing compacts of highly topologically ordered grains on the length scale of 1–3 nm with significant strain fields.

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.

Hydrogen-Induced Reduction in Medium Range Order of a-Si Thin Films Observed using Fluctuation Electron Microscopy

2004 ◽  
Vol 10 (S02) ◽  
pp. 802-803
Author(s):  
Lakshmi Narayana Nittala ◽  
Sreenivas Jayaraman ◽  
Brent A Sperling ◽  
John R Abelson
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Electron Microscopy

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

Nanometer-scale Structural Relaxation in Zr-based Bulk Metallic Glass

2007 ◽  
Vol 1048 ◽  
Author(s):  
Jinwoo Hwang ◽  
Hongbo Cao ◽  
Paul M. Voyles
Keyword(s):  
Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Range Order ◽  
Nanometer Scale ◽  
Length Scale ◽  
Scanning Calorimetry ◽  
Medium Range Order ◽  
Medium Range

AbstractWe investigated the influence of annealing on the nanometer-scale medium-range order in Zr54Cu38Al8 bulk metallic glass using fluctuation electron microscopy. Fluctuation microscopy experiments probing structure at a length scale of 1 nm show that the as-cast Zr bulk metallic glass contains significant medium range order. That structure is unchanged by annealing at 87% of the glass transition temperature for 24 hours, although that anneal does significantly change the differential scanning calorimetry trace.

Evidence from Simulations for Orientational Medium Range Order in Fluctuation-Electron-Microscopy Observations of a-Si

2004 ◽  
Vol 10 (S02) ◽  
pp. 820-821 ◽  
Author(s):  
Sanjay V. Khare ◽  
Serge M. Nakhmanson ◽  
Paul M. Voyles ◽  
Pawel Keblinski ◽  
John R. Abelson
Keyword(s):  
Electron Microscopy ◽  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Electron Microscopy

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

Medium-Range Order in High Al-content Amorphous Alloys Measured by Fluctuation Electron Microscopy

2003 ◽  
Vol 806 ◽  
Author(s):  
W. G. Stratton ◽  
J. Hamann ◽  
J. H. Perepezko ◽  
P. M. Voyles
Keyword(s):  
Electron Microscopy ◽  
Cold Rolling ◽  
Amorphous Alloys ◽  
Melt Spinning ◽  
Amorphous State ◽  
Structural Difference ◽  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Electron Microscopy

ABSTRACTWe have used fluctuation electron microscopy (FEM) to measure nanoscale mediumrange order in amorphous Al92Sm8. Samples of this amorphous alloy formed by rapid quenching (melt-spinning) show a high density of pure Al nanocrystals (>1020 m-3) after low temperature (< 250 °C) devitrification. In samples amorphized by deformation (cold-rolling), primary Al-crystallization does not occur. This difference in devitrification behavior suggests an underlying structural difference in the amorphous state. FEM is a quantitative microscopy technique for determining nanoscale medium-range order in amorphous materials. Our measurements show that amorphous alloys formed by melt-spinning and cold-rolling have significant structural differences, and that annealing melt-spun alloy under conditions previously shown to modify the devitrification thermodynamics also changes the medium-range structure.

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