scholarly journals Stability and molecular pathways to the formation of spin defects in silicon carbide

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Elizabeth M. Y. Lee ◽  
Alvin Yu ◽  
Juan J. de Pablo ◽  
Giulia Galli
Keyword(s):  
Silicon Carbide ◽  
Density Functional ◽  
Defect Formation ◽  
Density Functional Theory Calculations ◽  
Wide Bandgap ◽  
Enhanced Sampling ◽  
Functional Theory ◽  
Thermally Activated ◽  
Atomistic Models ◽  
Bandgap Semiconductors

AbstractSpin defects in wide-bandgap semiconductors provide a promising platform to create qubits for quantum technologies. Their synthesis, however, presents considerable challenges, and the mechanisms responsible for their generation or annihilation are poorly understood. Here, we elucidate spin defect formation processes in a binary crystal for a key qubit candidate—the divacancy complex (VV) in silicon carbide (SiC). Using atomistic models, enhanced sampling simulations, and density functional theory calculations, we find that VV formation is a thermally activated process that competes with the conversion of silicon (VSi) to carbon monovacancies (VC), and that VV reorientation can occur without dissociation. We also find that increasing the concentration of VSi relative to VC favors the formation of divacancies. Moreover, we identify pathways to create spin defects consisting of antisite-double vacancy complexes and determine their electronic properties. The detailed view of the mechanisms that underpin the formation and dynamics of spin defects presented here may facilitate the realization of qubits in an industrially relevant material.

Effects of S/Ce-codoping on electronic structures and optical properties of anatase TiO2 from density functional theory calculations

2015 ◽  
Vol 29 (35n36) ◽  
pp. 1550249
Author(s):  
Shi Wen Zhou ◽  
Jian Liu ◽  
Ping Peng ◽  
Wen Qin Chen
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Optical Absorption ◽  
Density Functional ◽  
Defect Formation ◽  
Dipole Moments ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Light Region ◽  
Rich Condition

The electronic and optical properties of S- and/or Ce-(co)doped anatase titanium dioxide (TiO2) are investigated using density functional theory plus U (DFT[Formula: see text]U) calculations. The optimized total energy suggests that TiO2 codoping by Ce and S favours the configuration of one substitutional Ce atom occupied on a Ti site with one substitutional S atom either on its nearest neighboring O or Ti site. The calculated results show that all doping configurations exhibit remarkable red-shift and excellent photocatalytic properties compared with pure TiO2. These reinforced features can mainly be ascribed to the appearance of S [Formula: see text] states in the top of valence band (VB) and Ce [Formula: see text] states in the bottom of conduction band (CB) as well as the contribution from the increasing octahedral dipole moments. The synergetic effects of cationic Ce and anionic S can extend optical absorption edge, which results in higher absorption coefficient in the visible light region than that of the anionic S monodoping and cationic Ce monodoping case; in the same time, decreasing the codoping concentration leads to reduced optical absorption. Additionally, Ce and S as cations incorporating into TiO2 lattices can induce stronger redox potential with a lower defect formation energy under O-rich condition compared with other doping systems.

scholarly journals Generative Design of Stable Semiconductor Materials Using Deep Learning And DFT

2022 ◽  
Author(s):  
Edirisuriya Siriwardane ◽  
Yong Zhao ◽  
Indika Perera ◽  
Jianjun Hu
Keyword(s):  
Deep Learning ◽  
High Throughput ◽  
Density Functional ◽  
Semiconductor Device ◽  
Wide Bandgap ◽  
Generative Adversarial Network ◽  
Functional Theory ◽  
Adversarial Network ◽  
Bandgap Semiconductors ◽  
Learning Data

Semiconductor device technology has exceptionally developed in complexity since discovering the bipolar transistor. With the rapid advancement of various technologies, semiconductors with distinct properties are essential. Recently, deep-learning, data-mining, and density functional theory (DFT)- based high-throughput calculations were widely performed to discover potential semiconductors for diverse applications. CubicGAN is a generative adversarial network where high-throughput analyses were done to uncover mechanically and dynamically stable materials with the assistance of DFT. In our work, we screened the semiconductors using a binary classifier from materials found from the CubicGAN. Next, we performed DFT computations to study their thermodynamic stability based on energy-above-hull and formation energy. According to our studies, 12 stable semiconductors were found with a particular class of materials, which we label as AA′MH6. Those are BaNaRhH6, BaSrZnH6, BaCsAlH6, SrTlIrH6, KNaNiH6, NaYRuH6, CsKSiH6, CaScMnH6, YZnMnH6, NaZrMnH6, AgZrMnH6, AgZrMnH6, and ScZnMnH6. It could be shown that AA′MH6 with M=Mn and NaYRuH6 semiconductors have considerably different structural, mechanical, and thermodynamic properties compared to the rest of the AA′MH6 semiconductors. In this study, The maximum bandgap found was approximately 3.3 eV from KNaNiH6, while the minimum bandgap was about 1.3 eV from CaScMnH6. BaNaRhH6, BaCsAlH6, CsKSiH6, KNaNiH6, and NaYRuH6 were identified as wide-bandgap semiconductors, where bandgaps are greater than 2 eV. Furthermore, BaSrZnH6 and KNaNiH6 are a direct bandgap semiconductors, whereas other AA′MH6 semiconductors exhibit indirect bandgaps.

A DFT study on the N2O reduction by CO molecule over silicon carbide nanotubes and nanosheets

RSC Advances ◽  
2016 ◽  
Vol 6 (64) ◽  
pp. 59091-59099 ◽  
Author(s):  
Parisa Nematollahi ◽  
Mehdi D. Esrafili
Keyword(s):  
Density Functional Theory ◽  
Silicon Carbide ◽  
Nitrous Oxide ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Dft Study ◽  
N2o Reduction ◽  
Functional Theory ◽  
Silicon Carbide Nanotubes

In this work, we study the nitrous oxide (N2O) reduction by CO over zigzag (6,0) silicon carbide nanotubes (SiCNT) and nanosheets (SiCNS) by means of density functional theory calculations.

Thermally activated surface oxygen defects at the perimeter of Au/TiO2: a DFT+U study

2015 ◽  
Vol 17 (38) ◽  
pp. 25403-25410 ◽  
Author(s):  
Muhammad Adnan Saqlain ◽  
Akhtar Hussain ◽  
Mohammad Siddiq ◽  
Ary R. Ferreira ◽  
Alexandre A. Leitão
Keyword(s):  
Density Functional Theory ◽  
Oxygen Atom ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Surface Oxygen ◽  
Functional Theory ◽  
Thermally Activated ◽  
Oxygen Defects ◽  
Model Surfaces ◽  
Activated Surface

Density functional theory calculations were performed to examine the formation of oxygen atom vacancies on three model surfaces namely, clean anatase TiO2(001) and, Au3 and Au10 clusters supported on anatase TiO2(001).

scholarly journals Photoluminescence line shapes for color centers in silicon carbide from density functional theory calculations

2021 ◽  
Vol 103 (12) ◽  
Author(s):  
Arsalan Hashemi ◽  
Christopher Linderälv ◽  
Arkady V. Krasheninnikov ◽  
Tapio Ala-Nissila ◽  
Paul Erhart ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Silicon Carbide ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Color Centers ◽  
Functional Theory ◽  
Line Shapes ◽  
Photoluminescence Line

On the Linear Geometry of Lanthanide Hydroxide (Ln—OH, Ln=La-Lu)

2019 ◽  
Author(s):  
Hassan Harb ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Triple Bond ◽  
Density Functional ◽  
Valence Electron ◽  
Density Functional Theory Calculations ◽  
Electron Configuration ◽  
Functional Theory ◽  
Key Species ◽  
Pi Orbitals ◽  
Lanthanide Hydroxide ◽  
Linear Geometry

Lanthanide hydroxides are key species in a variety of catalytic processes and in the preparation of corresponding oxides. This work explores the fundamental structure and bonding of the simplest lanthanide hydroxide, LnOH (Ln=La-Lu), using density functional theory calculations. Interestingly, the calculations predict that all structures of this series will be linear. Furthermore, these results indicate a valence electron configuration featuring an occupied sigma orbital and two occupied pi orbitals for all LnOH compounds, suggesting that the lanthanide-hydroxide bond is best characterized as a covalent triple bond.

On the Linear Geometry of Lanthanide Hydroxide (Ln—OH, Ln=La-Lu)

2019 ◽  
Author(s):  
Hassan Harb ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Triple Bond ◽  
Density Functional ◽  
Valence Electron ◽  
Density Functional Theory Calculations ◽  
Electron Configuration ◽  
Functional Theory ◽  
Key Species ◽  
Pi Orbitals ◽  
Lanthanide Hydroxide ◽  
Linear Geometry

Lanthanide hydroxides are key species in a variety of catalytic processes and in the preparation of corresponding oxides. This work explores the fundamental structure and bonding of the simplest lanthanide hydroxide, LnOH (Ln=La-Lu), using density functional theory calculations. Interestingly, the calculations predict that all structures of this series will be linear. Furthermore, these results indicate a valence electron configuration featuring an occupied sigma orbital and two occupied pi orbitals for all LnOH compounds, suggesting that the lanthanide-hydroxide bond is best characterized as a covalent triple bond.

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