Properties of multicomponent amorphous silicon forming a tetrahedrally-bonded continuous random network

1983 ◽  
Vol 59-60 ◽  
pp. 549-552 ◽  
Author(s):  
Katsumi Murase ◽  
Toshio Ogino ◽  
Yoshihiko Mizushima
1998 ◽  
Vol 540 ◽  
Author(s):  
J. M. Gibson ◽  
J-Y. Cheng ◽  
P. Voyles ◽  
M.M.J. TREACY ◽  
D.C. Jacobson

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.


1982 ◽  
Vol 14 ◽  
Author(s):  
D. K. Biegelsen

ABSTRACTIn this paper we argue that amorphous silicon can be treated as a relaxed continuous random network. The optical and electronic properties are controlled by localized gap states which arise from characteristic features of a disordered tetrahedrally-bonded covalent network. Experimental results are reviewed which indicate that the dominant (perhaps only) electrically-active defect in hydrogenated amorphous silicon is the topologically distinct, silicon dangling bond. Finally, we suggest that the same, disorder-related characteristics might also typify the electronic properties of some macroscopic crystalline silicon defects.


1999 ◽  
Vol 5 (S2) ◽  
pp. 682-683
Author(s):  
J.M. Gibson ◽  
M.M.J. Treacy ◽  
P.M. Voyles

When I (JMG) began my Ph.D. studies under the supervision of Archie Howie in 1975, he was still licking his wounds over one of the very few apparently incorrect publications[l] of his career. I am proud that our recent work has shown that, far from being wrong, Archie and Lee Rudee were actually 25 years before their time. It was in the early 1970’s that electron microscopy instrumentation reached the performance level that was adequate to resolve the interplanar spacings in elemental materials, such as the semiconductors silicon and germanium. It immediately became of interest to examine the structure of amorphous silicon and germanium, in the expectation that direct imaging could resolve the old controversy between micro-crystallite and random network structural models. Porai-Koschits was the first to suggest that amorphous materials comprised extremely small crystalline domains (microcrystals), in contrast Zachariasen[2] proposed that a continuous random network was a better description of glassy materials.


2018 ◽  
Vol 51 (6) ◽  
pp. 1544-1550
Author(s):  
Aly Rahemtulla ◽  
Bruno Tomberli ◽  
Stefan Kycia

The atomic arrangements in amorphous solids, unlike those in crystalline materials, remain elusive. The details of atom ordering are under debate even in simplistic random network models. This work presents further advancements in the local atomic motif (LAM) method, first through the introduction of an optimized alignment procedure providing a clearer image of the angular ordering of atoms in a model. Secondly, by applying stereographic projections with LAMs, the angular ordering within coordination shells can be quantified and investigated. To showcase the new capabilities, the LAM method is applied to amorphous germanium, the archetype of covalent amorphous systems. The method is shown to dissect structural details of amorphous germanium (a-Ge) from the continuous random network (CRN) model and a reverse Monte Carlo (RMC) refined model fitted to high-resolution X-ray scattering measurements. The LAMs reveal well defined dihedral ordering in the second shell. The degree of dihedral ordering is observed to be coupled to bond length distances in the CRN model. This coupling is clearly not present within the RMC refined model. The LAMs reveal inclusions of third-shell atoms occupying interstitial positions in the second shell in both models.


2001 ◽  
Vol 7 (S2) ◽  
pp. 226-227
Author(s):  
P. M. Voyles ◽  
D. A. Muller

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.


1999 ◽  
Vol 59 (5) ◽  
pp. 3540-3550 ◽  
Author(s):  
Ming-Zhu Huang ◽  
Lizhi Ouyang ◽  
W. Y. Ching

1975 ◽  
Vol 17 (3) ◽  
pp. 299-318 ◽  
Author(s):  
J.F. Graczyk ◽  
P. Chaudhari

1974 ◽  
Vol 15 (2) ◽  
pp. 199-214 ◽  
Author(s):  
P Steinhardt ◽  
R Alben ◽  
D Weaire

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