Microscopic Nature of Nature Light Induced Defects

1998 ◽  
Vol 507 ◽  
Author(s):  
R. Biswas ◽  
B. C. Pana
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Bond Angle ◽  
Dangling Bonds ◽  
Defect Complexes ◽  
Dynamics Simulations ◽  
Induced Defects

ABSTRACTMolecular dynamics simulations find light-induced metastable defects to be silicon dangling bonds accompanied by (Si-H)2 defect complexes that have two Si-H bonds. These complexes are formed by pairs of hydrogen breaking a silicon bond. This supports the model of Branz. These defects are the analogue of the H2* defect in c-Si and their energy correlates with the bond-angle strain. Several features of annealing including E-field induced effects are well accounted for by the (Si-H)2 defect.

First Principles Molecular Dynamics Studies of a-Si and a-Si:H

1993 ◽  
Vol 297 ◽  
Author(s):  
P.A. Fedders
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
First Principles ◽  
Energy Gap ◽  
Dangling Bonds ◽  
Dynamics Simulations ◽  
Induced Defects ◽  
First Principles Molecular Dynamics

We give a brief description of the various classes of molecular dynamics simulations and then describe what we have learned from our simulations recently. This includes information on the nature of defects in a-Si:H including positions in the energy gap and localization, relaxation and rearrangement effects, light induced defects, and the motion of H atoms and Si dangling bonds.

A method to apply bond‐angle constraints in molecular dynamics simulations

2020 ◽  
Author(s):  
Maria Pechlaner ◽  
Andreas P. Dorta ◽  
Zhixiong Lin ◽  
Victor H. Rusu ◽  
Wilfred F. Gunsteren
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Bond Angle ◽  
Dynamics Simulations

scholarly journals Structure and Stability of Microvoids in a-Si:H

1993 ◽  
Vol 297 ◽  
Author(s):  
R. Biswas ◽  
I. Kwon
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structural Properties ◽  
Small Angle ◽  
Limited Range ◽  
Dangling Bonds ◽  
X Ray ◽  
X Ray Scattering ◽  
Internal Surfaces ◽  
Dynamics Simulations

Microvoids have been observed in a-Si:H as demonstrated by small angle X-ray scattering. We have studied the structural properties of these microvoids with molecular dynamics simulations. Using molecular dynamics simulations with classical potentials, we have created microvoids by removing Si and H atoms from a computer generated a-Si:H network. The internal surfaces of the microvoids were passivated with additional H atoms and the microvoids were fully relaxed. Microvoids over a limited range of sizes (5-90 missing atoms) were examined. We obtained a relaxed microvoid structure with no dangling bonds for a microvoid with 17 missing atoms, whereas other sizes examined produced less relaxed models with short H-H distances at the microvoid surface. The strains near the microvoid surface are described. The microvoid model was stable to local excitations on weak bonds in the vicinity of the microvoid.

scholarly journals Molecular Dynamics Simulations of Heavy Ion Induced Defects in SiC Schottky Diodes

2018 ◽  
Vol 18 (3) ◽  
pp. 481-483 ◽  
Author(s):  
Arto Javanainen ◽  
Henrique Vazquez Muinos ◽  
Kai Nordlund ◽  
Flyura Djurabekova ◽  
Kenneth F. Galloway ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Schottky Diodes ◽  
Heavy Ion ◽  
Dynamics Simulations ◽  
Induced Defects

scholarly journals Origin of short- and medium-range order in supercooled liquid Ge3Sb2Te6 using ab initio molecular dynamics simulations

2020 ◽  
Vol 22 (17) ◽  
pp. 9759-9766
Author(s):  
Chong Qiao ◽  
Y. R. Guo ◽  
Songyou Wang ◽  
Yu Jia ◽  
Cai-Zhuang Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Bond Angle ◽  
Supercooled Liquid ◽  
Range Order ◽  
Ab Initio Molecular Dynamics ◽  
Medium Range Order ◽  
Medium Range ◽  
Dynamics Simulations

The disordered clusters in Ge3Sb2Te6 change to ordered octahedrons by adjustment of the bond-angle relationship as the temperature decreases.

The Atomistic and Quantum Mechanical Origins of Light-Induced Defects in a-Si

1992 ◽  
Vol 258 ◽  
Author(s):  
P. A. Fedders ◽  
Y. Fu ◽  
D. A. Drabold
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Mechanical Model ◽  
Quantum Mechanical ◽  
Dangling Bond ◽  
Localized State ◽  
Dynamics Simulations ◽  
Staebler Wronski Effect ◽  
Induced Defects

ABSTRACTWe present an atomistic and quantum mechanical model of light-induced defects (the Staebler-Wronski effect). The model is based in part on our observations of molecular dynamics simulations with an ab initio code and requires a change in the charge of a well localized state in the gap, such as a dangling bond, to nucleate the new defects. Besides the new defects, a substantial rearrangement of the supercell is observed.

A Case for Molecular Hydrogen Being the Mobile H Species in a-Si:H

2000 ◽  
Vol 609 ◽  
Author(s):  
P. A. Fedders
Keyword(s):  
Activation Energy ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Molecular Hydrogen ◽  
Hydrogen Diffusion ◽  
Hydrogen Transport ◽  
Mobile Species ◽  
Standard Picture ◽  
Dynamics Simulations ◽  
Induced Defects

ABSTRACTThe mechanism (or mechanisms) of hydrogen transport in a-Si:H is of great intrinsic interest but is also important for the understanding of a number of phenomena such as light induced defects. We find that the literature includes many calculations for the activation energy for hydrogen diffusion that are at best misleading and often interpreted incorrectly. In this paper we summarize a number of calculations that apply to particles hopping in complex media and apply the results to a-Si:H. These calculations, coupled with existing estimates of the energy of various H configurations in a-Si:H, show that the standard picture is likely to be incorrect. However, previous work on the mobility of molecular hydrogen in crystalline Si coupled with some molecular dynamics simulations presented in this paper show that the mobile species of hydrogen in a-Si:H may well be molecular.

Results from First Principles Molecular Dynamics Simulations on a-Si

1991 ◽  
Vol 219 ◽  
Author(s):  
Peter A. Fedders ◽  
David D. Drabold
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Conduction Band ◽  
First Principles ◽  
Band Tailing ◽  
Dynamics Simulations ◽  
Induced Defects ◽  
First Principles Molecular Dynamics

ABSTRACTWe report on some recent results of first principles molecular dynamics simulations on a-Si. These simulations yield interesting results that challenge the standard beliefs about what constitutes a defect, how light induced defects arise, and about the origins of conduction band tailing.

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