Search query: Two-dimensional  carbon  semiconductor:  Density functional theory calculations

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abstract: We show that patterned defects can be used to disrupt the sublattice symmetry of graphene so as to open up a band gap. This way of modifying graphene's electronic structure does not rely on external agencies, the addition of new elements or special boundaries. The method is used to predict a planar, low energy, graphene allotrope with a band gap of 1.2 eV. This defect engineering also allows semiconducting ribbons of carbon to be fabricated within graphene. Linear arrangements of defects lead to naturally embedded ribbons of the semiconducting material in graphene, offering the prospect of two dimensional circuit logic composed entirely of carbon.
author_names: David J Appelhans

Zhibin Lin

Mark T Lusk
title: Two dimensional carbon semiconductor: Density functional theory calculations
year: 2010

abstract: Abstract A recently proposed two dimensional (2D) carbon allotrope, tetrahex carbon, draws scientific attention due to its remarkable electronic and mechanical properties. This 2D carbon structure consists of tetragonal and hexagonal rings, and exhibits excellent semiconductor properties including a finite direct band gap and high carrier mobility, suggesting potential applications in semiconductor devices. In this paper, the electronic properties of fluorine/hydrogen adsorbed tetrahex C was investigated via first principles density functional theory calculations. It demonstrates that its band structure can be significantly tuned and could be metallic with dangling bonds from F/H adsorption. With increasing F/H adsorption density, it shows semiconducting behavior and the band gap is widening, mainly due to the sp2 bonded carbon being gradually converted to sp3 hybridization. It was also found that effective masses of charge carriers along the zigzag direction can largely reduce through adsorption of F/H, leading to potentially enhanced carrier mobility. Tetrahex C shows prominent anisotropicity and the tunability of effective masses through F/H adsorption is remarkably dependent on the crystal orientation. In addition, it was found that, the work function of the F adsorbed tetrahex C increases while electron affinity decreases, compared to the pristine one. However, the H covered carbon film shows significant reductions of both work function and electron affinity.
author_names: Yingguo Yang

Guang Yang

Xihong Peng
title: Electronic properties of fluorine/hydrogen adsorbed two dimensional tetrahex carbon: A first principles study
year: 2020

abstract: A new two dimensional boron carbon nitrogen (BCN) structure is predicted and is theoretically investigated based on density functional theory. The BCN structure belongs to the space group C222, and is composed of twelve B, twelve C and twelve N atoms per orthorhombic cell (named oC B12C12N12) It consists of small hollow spheres with two hexagons per sphere. The dynamical, thermal and mechanical stabilities of oC B12C12N12 are respectively evaluated by phonon spectroscopy, ab initio molecular dynamics calculations and elastic constant measurements. The simulated in plane stiffness and Poisson ratio display anisotropic features. The band structure shows that oC B12C12N12 is a direct semiconductor with a gap of 2.72 eV (GW) oC B12C12N12 has an absorption range from the visible light spectrum to the ultraviolet. Therefore, due to its small direct band gap and optical absorption, oC B12C12N12 may be a good candidate for electronic and optical applications.
author_names: Yihua Lu

Xi Zhu

Maoyan Wang
title: Theoretical investigations of a new two dimensional semiconducting boron carbon nitrogen structure
year: 2020

abstract: Abstract Twin graphene is a novel two dimensional semiconducting carbon allotrope with an intrinsic direct bandgap. To explore the excellent properties and potential applications of twin graphene, we performed first principle density functional theory calculations on the structural, electronic, and magnetic properties of twin graphene with dual doping of Al and Y (Y B, N, O) atoms at different sites (ortho, meta, and para) The combined processes of the formation of all Al Y dual doped twin graphene (AlY TG) systems are exothermic and form stable dual doped structures, and the most stable structure is the AlB TG system. For the B, N, or O atoms at the same doped site, the stability decreases in the order of AlB TG, AlN TG, and AlO TG. Dual doping regulates the bandgap of twin graphene in the cases of AlB and AlN doping. A transition from a semiconducting material into a metal is observed when AlO doping is used, while a transition from a direct semiconductor into an indirect semiconductor is observed for AlB doping at the ortho site. Different magnetic moments of the AlY TG systems are observed for different Y atoms placed at different doping sites. The AlN TG system remains nonmagnetic, while the AlB TG system has a magnetic moment of 1.01 mB only in the meta site, and the AlO TG systems have magnetic moments of 0.50 mB and 0.56 mB in the ortho and meta sites, respectively. Moreover, different doping concentrations can effectively affect the electronic structures and magnetisms of the AlY TG systems. For doping concentrations of 5.6% and 11.1% at the meta site, the AlB TG systems exhibit metal characteristics with a high spin polarization. The results show that the electronic and magnetic properties of twin graphene can be modulated via Al Y (Y B, N, O) dual doping, indicating that twin graphene has potential applications in nanomagnets and spintronics devices.
author_names: Bing Yu

You Xie

Xiu Wu

Yue Gao

Su-fang Wang

Jian-Min Zhang
title: Structural and electronic properties of AlY (Y B, N, O) dual doped twin graphene: A density functional theory study
year: 2021

abstract: Graphitic carbon nitride has been predicted to be structurally analogous to carbon only graphite, yet with an inherent bandgap. We have grown, for the first time, macroscopically large crystalline thin films of triazine based, graphitic carbon nitride (TGCN) using an ionothermal, interfacial reaction starting with the abundant monomer dicyandiamide. The films consist of stacked, two dimensional (2D) crystals between a few and several hundreds of atomic layers in thickness. Scanning force and transmission electron microscopy show long range, in plane order, while optical spectroscopy, X ray photoelectron spectroscopy, and density functional theory calculations corroborate a direct bandgap between 1.6 and 2.0 eV. Thus TGCN is of interest for electronic devices, such as field effect transistors and light emitting diodes.
author_names: Gerardo Algara-Siller

Nikolai Severin

Samantha Yu-Ling Chong

Torbjorn Bjorkman

Robert G Palgrave

Andrea Laybourn

Markus Antonietti

Yaroslav Z Khimyak

Arkady V Krasheninnikov

Jurgen P Rabe

Ute Kaiser

Andrew I Cooper

Arne Thomas

Michael J Bojdys
title: Triazine based graphitic carbon nitride: a two dimensional semiconductor.
venue: Angewandte Chemie
year: 2014

abstract: Two dimensional (2D) semiconductors, such as graphitic carbon nitride (g C3N4) molybdenum disulfide (MoS2) and phosphorene, with desirable optoelectronic properties and large photoreactive contact area for light absorption, have been widely used as donors and acceptors in high quality heterojunction solar cells. In this work, by using first principles density functional theory calculations, we demonstrate that tellurene is a promising candidate 2D semiconductor for designing highly efficient solar cells due to its desirable optoelectronic properties (an ideal band gap of 1.47 eV, a high carrier mobility up to 2.87 x 103 cm2 V 1 s 1, strong visible light absorption up to 5.0 x 105 cm 1 and high stability in ambient conditions) superior to existing 2D semiconductors used in solar cells. Furthermore, we find that tellurene and TMDs show desirable type II band alignment for constructing highly efficient heterojunction solar cells with strong charge separation and enhanced sunlight absorption. In particular, the calculated maximum power conversion efficiency (PCE) of our designed Te/WTe2 and Te/MoTe2 heterojunction solar cells can reach as high as 22.5% and 20.1% respectively.
author_names: Kai-Hsin Wu

Huanhuan Ma

Yunzhi Gao

Wei Hu

Jinlong Yang
title: Highly efficient heterojunction solar cells based on two dimensional tellurene and transition metal dichalcogenides
year: 2019

abstract: Designing new two dimensional (2D) materials with novel band topologies has continuously attracted intense interest in fundamental science and potential applications. Here, we report a unique 2D Mg2C monolayer featuring quasi planar hexa coordinate magnesium and hexa coordinate carbon, which can be tuned from a metal to a semiconductor. The system has been studied using density functional theory, including electronic structure calculations and molecular dynamics simulations. In the freestanding state, the Mg2C monolayer behaves as a weak metal; however, by increasing the biaxial tensile strains, it can gradually be modulated to a gapless semimetal and then to a semiconductor. The Mg2C monolayer exhibits excellent dynamic and thermal stabilities and is also the global minimum of the 2D Mg2C system, implying the feasibility of its experimental synthesis. With unique band structures, the material may find applications in optoelectronics and electromechanics.
author_names: Lingbiao Meng

Shuang Ni

Minjie Zhou

Yingjuan Zhang

Zhaoguo Li

Weidong Wu
title: Metal semiconductor transition of two dimensional Mg2C monolayer induced by biaxial tensile strain.
venue: Physical chemistry chemical physics PCCP
year: 2017

abstract: The existence of two novel hybrid two dimensional (2D) monolayers, 2D B3C2P3 and 2D B2C4P2, has been predicted based on the density functional theory calculations. It has been shown that these materials possess structural and thermodynamic stability. 2D B3C2P3 is a moderate band gap semiconductor, while 2D B2C4P2 is a zero band gap semiconductor. It has also been shown that 2D B3C2P3 has a highly tunable band gap under the effect of strain and substrate engineering. Moreover, 2D B3C2P3 produces low barriers for dissociation of water and hydrogen molecules on its surface, and shows fast recovery after desorption of the molecules. The novel materials can be fabricated by carbon doping of boron phosphide and directly by arc discharge and laser ablation and vaporization. Applications of 2D B3C2P3 in renewable energy and straintronic nanodevices have been proposed.
author_names: Andrey A Kistanov

Stepan A Shcherbinin

Svetlana V Ustiuzhanina

Marko Huttula

Wei Cao

Vladimir R Nikitenko

Oleg V Prezhdo
title: First Principles Prediction of Two Dimensional B3C2P3 and B2C4P2: Structural Stability, Fundamental Properties, and Renewable Energy Applications.
venue: The journal of physical chemistry letters
year: 2021

abstract: A new carbon based two dimensional crystalline nanostructure was discovered. The nanostructure was facilely constructed by chemical vapor deposition of benzene on Cu(111) in an ultrahigh vacuum chamber. A low temperature scanning tunneling microscopy and spectroscopy study of the nanostructure indicated that it has an orthorhombic superstructure and a semiconductor character with an energy gap of 0.8 eV. An X ray photoelectron spectroscopy study showed that C C(sp(2) bonding is predominantly preserved, suggesting a framework consisting of p conjugated building blocks. The periodic nanostructure was found to be a surprisingly excellent template for isolating and stabilizing magnetic atoms: Co atoms deposited on it can be well dispersed and form locally ordered atomic chains with their atomic magnetism preserved. Therefore the nanostructure may be suitable for organic spintronic applications. The most likely structural model for the nanostructure is proposed with the aid of density functional theory calculations and simulations, suggesting that the 2D nanostructure may consist of polyphenylene chains interconnected by Cu adatoms.
author_names: Qi Han

Huan Shan

Jialiang Deng

Aidi Zhao

Bing Wang

J G Hou
title: Construction of carbon based two dimensional crystalline nanostructure by chemical vapor deposition of benzene on Cu(111)
venue: Nanoscale
year: 2014

abstract: Abstract Graphitic carbon nitride (g C3N4, GCN) shows excellent photocatalytic activity for a myriad of reactions due to its unique traits and semiconducting properties. The design of a semiconductor heterojunction by hybridizing GCN and other materials with appropriate band structures has profiled one of the most fascinating approaches to enhance the photocatalytic efficiency of GCN. In our simulation, a metal free heterojunction was developed by incorporating zero dimensional (0D) black phosphorus quantum dots (BPQDs) with two dimensional (2D) GCN. The 0D/2D BPQD/GCN heterojunction was systematically investigated by using density functional theory (DFT) calculations. Various orientations of BPQD on GCN were compared. The electronic structure and charge density distribution of the BPQD/GCN composite were calculated to examine the most favorable configuration. Furthermore, the charge separation and transfer mechanism of this heterojunction structure were discussed from the perspective of computation. Our study reveals that BPQDs and GCN formed a Type II heterojunction with a high stability and robust photocatalytic efficiency. Overall, the present work not only elucidates theoretical guidance for taking the merits of BPQDs and GCN, but also paves a new frontier for engineering metal free 0D/2D heterojunction nanocomposite systems.
author_names: Zhouzhou Kong

Xingzhuo Chen

Wee-Jun Ong

Xiujian Zhao

Neng Li
title: Atomic level insight into the mechanism of 0D/2D black phosphorus quantum dot/graphitic carbon nitride (BPQD/GCN) metal free heterojunction for photocatalysis
year: 2019