New Model for Local H-Atom Bonding Re-Arrangements Associated with the Staebler-Wronski Effect in a-Si:H and a-Si:H-Based Alloys

ABSTRACTMany photoelectronic properties of a-Si,N:H alloys prepared by remote PECVD (RPECVD) from two N-atom source gases - N2 and NH3 - are the same; however, the photo-induced changes in the electrical properties in alloys with -2.1 eV bandgaps are ∼3 to 5 times greater in alloys deposited from NH3, which display Si-NH, as well as SiH bonding. Based on this result, we show that bonding groups important in the Staebler-Wronski effect include (i) ≡SiH, and nearest-neighbor (ii) ≡Si-NH-Sis and/or ≡Si-O-Sis in which the respective N and O-atoms make H-bonds with the sSiH group. The model, based on ab-initio calculations, includes a H-exchange reaction in which trapping of photo-generated holes promotes a transfer of the H-atom from the ^SiH group to a nearest-neighbor ≡Si-NH-Si≡ creating (i) a Si-dangling bond (Si*) and (ii) a Metastable (≡Si-NH2-Si≡) + group. Calculations indicate that neutral (≡Si-NH2≡Sis) ° is unstable, so that relaxation of (≡Si-NH2-Si≡) + groups can occur by trapping of a thermally-released (trapped) electron during a post-light-soaking thermal-anneal. The same type of model is developed for hole/electron trapping-induced H-atom transfer between ≡SiH and ≡Si-0-Si≡ groups in other a-Si:H Materials.

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Pressure-induced changes in local electronic structures of SiO2 and MgSiO3 polymorphs: Insights from ab initio calculations of O K-edge energy-loss near-edge structure spectroscopy

American Mineralogist ◽

10.2138/am.2012.3943 ◽

2012 ◽

Vol 97 (5-6) ◽

pp. 897-909 ◽

Cited By ~ 13

Author(s):

Y. S. Yi ◽

S. K. Lee

Keyword(s):

Energy Loss ◽

Ab Initio Calculations ◽

Ab Initio ◽

Electronic Structures ◽

Edge Structure ◽

Induced Changes

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STRUCTURE AND MAGNETIC PROPERTIES IN RUTHENIUM-BASED FULL-HEUSLER ALLOYS: AB INITIO CALCULATIONS

Modern Physics Letters B ◽

10.1142/s0217984913502199 ◽

2013 ◽

Vol 27 (30) ◽

pp. 1350219 ◽

Cited By ~ 1

Author(s):

S. BAHLOULI ◽

Z. AARIZOU ◽

M. ELCHIKH

Keyword(s):

Magnetic Properties ◽

Ab Initio Calculations ◽

Ab Initio ◽

Nearest Neighbor ◽

Heusler Alloys ◽

Full Potential ◽

Type I ◽

Type Ii ◽

Full Heusler ◽

Full Heusler Alloys

In this paper, we present ab initio calculations within density functional theory (DFT) to investigate structure, electronic and magnetic properties of Ru 2 CrZ ( Z = Si , Ge and Sn ) full-Heusler alloys. We have used the developed full-potential linearized muffin tin orbitals (FP-LMTO) based on the local spin density approximation (LSDA) with the PLane Wave expansion (PLW). In particular, we found that these Ruthenium-based Heusler alloys have the antiferromagnetic (AFM) type II as ground state. Then, we studied and discussed the magnetic properties belonging to our different magnetic structures: AFM type II, AFM type I and ferromagnetic (FM) phase. We also found that Ru 2 CrSi and Ru 2 CrGe exhibit a semiconducting behavior whereas Ru 2 CrSn has a semimetallic-like behavior as it is experimentally found. We made an estimation of Néel temperatures (T N ) in the framework of the mean-field theory and used the energy differences approach to deduce the relevant short-range nearest-neighbor (J1) and next-nearest-neighbor (J2) interactions. The calculated T N are somewhat overestimated to the available experimental ones.

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Identification of intrinsic electron trapping sites in bulk amorphous silica from ab initio calculations

Microelectronic Engineering ◽

10.1016/j.mee.2013.03.027 ◽

2013 ◽

Vol 109 ◽

pp. 68-71 ◽

Cited By ~ 23

Author(s):

Al-Moatasem El-Sayed ◽

Matthew B. Watkins ◽

Alexander L. Shluger ◽

Valeri V. Afanas’ev

Keyword(s):

Ab Initio Calculations ◽

Ab Initio ◽

Amorphous Silica ◽

Electron Trapping ◽

Trapping Sites

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Hydrogen induced changes in structural properties of iron: Ab initio calculations

Advances in Modeling Concrete Service Life ◽

10.1007/978-94-007-2703-8_8 ◽

2011 ◽

pp. 79-84 ◽

Cited By ~ 2

Author(s):

Alejandro Castedo ◽

Javier Sanchez ◽

José Fullea ◽

Carmen Andrade ◽

Pedro Luis Andres

Keyword(s):

Ab Initio Calculations ◽

Ab Initio ◽

Structural Properties ◽

Induced Changes

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The electronic, magnetic and electrical properties of Mn2FeReO6: Ab-initio calculations and Monte-Carlo simulation

Journal of Magnetism and Magnetic Materials ◽

10.1016/j.jmmm.2019.165833 ◽

2020 ◽

Vol 495 ◽

pp. 165833 ◽

Cited By ~ 6

Author(s):

M. Kibbou ◽

Y. Benhouria ◽

M. Boujnah ◽

I. Essaoudi ◽

A. Ainane ◽

...

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Electrical Properties ◽

Ab Initio Calculations ◽

Ab Initio ◽

Magnetic And Electrical Properties

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

MRS Proceedings ◽

10.1557/proc-258-335 ◽

1992 ◽

Vol 258 ◽

Cited By ~ 1

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.

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Environmental screening and ligand-field effects to magnetism in CrI3 monolayer

npj Computational Materials ◽

10.1038/s41524-021-00631-4 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

D. Soriano ◽

A. N. Rudenko ◽

M. I. Katsnelson ◽

M. Rösner

Keyword(s):

Ab Initio Calculations ◽

Ab Initio ◽

Nearest Neighbor ◽

Hexagonal Boron Nitride ◽

Magnetic Moments ◽

Random Phase ◽

Exchange Interactions ◽

Ligand Field ◽

Hubbard Models ◽

Microscopic Origin

AbstractWe study the microscopic origin of magnetism in suspended and dielectrically embedded CrI3 monolayer by down-folding minimal generalized Hubbard models from ab initio calculations using the constrained random phase approximation. These models are capable of describing the formation of localized magnetic moments in CrI3 and of reproducing electronic properties of direct ab initio calculations. Utilizing the magnet force theorem, we find a multi-orbital super-exchange mechanism as the origin of magnetism in CrI3 resulting from an interplay between ferro- and anti-ferromagnetic Cr-Cr d coupling channels, which is decisively affected by the ligand p orbitals. We show how environmental screening, such as resulting from encapsulation with hexagonal boron nitride, affects the Coulomb interaction in the film and how this controls its magnetic properties. Driven by a non-monotonic interplay between nearest and next-nearest neighbor exchange interactions we find the magnon dispersion and the Curie temperature to be non-trivially affected by the environmental screening.

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