scholarly journals A new photodetector structure based on graphene nanomeshes: an ab initio study

2020 ◽  
Vol 11 ◽  
pp. 1036-1044
Author(s):  
Babak Sakkaki ◽  
Hassan Rasooli Saghai ◽  
Ghafar Darvish ◽  
Mehdi Khatir
Keyword(s):  
Infrared Detectors ◽  
Density Functional ◽  
Tight Binding ◽  
Optical Devices ◽  
Functional Theory ◽  
Semiconducting Properties ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Non Equilibrium Green’S Function ◽  
Insight Into

Recent experiments suggest graphene-based materials as candidates in future electronic and optoelectronic devices. In this paper, we propose to investigate new photodetectors based on graphene nanomeshes (GNMs). Density functional theory (DFT) calculations are performed to gain insight into electronic and optical characteristics of various GNM structures. To investigate the device-level properties of GNMs, their current–voltage characteristics are explored by DFT-based tight-binding (DFTB) in combination with non-equilibrium Green’s function (NEGF) methods. Band structure analysis shows that GNMs have both metallic and semiconducting properties depending on the arrangements of perforations. Also, absorption spectrum analysis indicates attractive infrared peaks for GNMs with semiconducting characteristics, making them better photodetectors than graphene nanoribbon (GNR)-based alternatives. The results suggest that GNMs can be potentially used in mid-infrared detectors with specific detectivity values that are 100-fold that of graphene-based devices and 1000-fold that of GNR-based devices. Hence, the special properties of graphene combined with the quantum feathers of the perforation makes it suitable for optical devices.

The switching behaviors induced by torsion angle in a diblock co-oligomer molecule with tailoring graphene nanoribbon electrodes

2018 ◽  
Vol 32 (04) ◽  
pp. 1850036 ◽  
Author(s):  
Aiyun Yang ◽  
Caijuan Xia ◽  
Boqun Zhang ◽  
Jun Wang ◽  
Yaoheng Su ◽  
...  
Keyword(s):  
Transport Properties ◽  
Electronic Transport ◽  
Torsion Angle ◽  
Density Functional ◽  
Graphene Nanoribbon ◽  
Molecular Device ◽  
Functional Theory ◽  
Electronic Transport Properties ◽  
Current Voltage ◽  
Current Voltage Characteristics

By applying first-principles method based on density functional theory combined with nonequilibrium Green’s function, we investigate the effect of torsion angle on the electronic transport properties in dipyrimidinyl–diphenyl co-oligomer molecular device with tailoring graphene nanoribbon electrodes. The results show that the torsion angle plays an important role on the electronic transport properties of the molecular device. When the torsion angle rotates from 0[Formula: see text] to 90[Formula: see text], the molecular devices exhibit very different current–voltage characteristics which can realize the on and off states of the molecular switch.

scholarly journals Calculation of CO adsorption capacity of single iron(II)- porphyrin and related electron transfer behavior by DFT theory

2020 ◽  
Author(s):  
Placido G. Mineo
Keyword(s):  
Density Functional ◽  
Co Adsorption ◽  
Molecular Wires ◽  
Molecular Wire ◽  
Dft Theory ◽  
Functional Theory ◽  
Current Voltage ◽  
End Groups ◽  
Transfer Behavior ◽  
Current Voltage Characteristics

The effect of CO adsorption on the electron transport behavior of single iron(II)-porphyrin molecular wire with sulfur end groups bonded to two gold electrodes isinvestigated using nonequilibrium Green's function formalism combined with firstprinciples density functional theory. The current-voltage characteristics of the singleFe-porphyrin molecular wires with and without CO adsorption are calculated. Theresults demonstrate that Fe-porphyrin molecular wire shows a negative differentialresistance (NDR) at 2.0 V

scholarly journals Current–voltage characteristics of borophene and borophane sheets

2017 ◽  
Vol 19 (32) ◽  
pp. 21461-21466 ◽  
Author(s):  
Sahar Izadi Vishkayi ◽  
Meysam Bagheri Tagani
Keyword(s):  
Density Functional Theory ◽  
Green's Function ◽  
Density Functional ◽  
Theoretical Research ◽  
Functional Theory ◽  
Nonequilibrium Green's Function ◽  
Function Formalism ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Green's Function Formalism

Motivated by recent experimental and theoretical research on a monolayer of boron atoms, borophene, the current–voltage characteristics of three different borophene sheets, 2Pmmn, 8Pmmn, and 8Pmmm, are calculated using density functional theory combined with the nonequilibrium Green’s function formalism.

FIRST-PRINCIPLES STUDY ON PHOTOSWITCHING BEHAVIOR IN SINGLE MOLECULE JUNCTION

2018 ◽  
Vol 25 (03) ◽  
pp. 1850070 ◽  
Author(s):  
BAO-AN BIAN ◽  
YA-PENG ZHENG ◽  
PEI-PEI YUAN ◽  
BIN LIAO ◽  
YU-QIANG DING
Keyword(s):  
Single Molecule ◽  
First Principles ◽  
Density Functional ◽  
Molecular Switch ◽  
Functional Theory ◽  
Current Voltage ◽  
Molecule Junction ◽  
Single Molecule Junction ◽  
Close Form ◽  
Non Equilibrium Green’S Function

We carry out first-principles calculations based on density functional theory and non-equilibrium Green’s function to investigate the electronic transport properties of a diarylethene-based molecule sandwiched between two Au electrodes. This molecular switch can be reversed between open and close forms by using light stimulation. We analyze the switch behavior of these two forms through the current–voltage curves, transmission spectra and molecular projected self-consistent Hamiltonian. It has been found that the current of the close form is significantly larger than the open form, and there is a large and stable switch ratio in a wide bias window. This result indicates that this molecule can become one of the good candidates for optical molecular switch in the future.

scholarly journals An ab initio study of small gas molecule adsorption on the edge of N-doped sawtooth penta-graphene nanoribbons

2021 ◽  
Vol 13 ◽  
pp. 130003
Author(s):  
Thanh Tien Nguyen ◽  
Le Vo Phuong Thuan ◽  
Tran Yen Mi
Keyword(s):  
Density Functional ◽  
Graphene Nanoribbons ◽  
Energy Charge ◽  
Functional Theory ◽  
Current Voltage ◽  
Gas Molecule ◽  
Gas Molecules ◽  
Toxic Gas ◽  
Carbon Dioxide Co2 ◽  
Non Equilibrium Green’S Function

Adsorption of the toxic gas molecules carbon monoxide (CO), carbon dioxide (CO2) and ammonia (NH3 ) on the edge of N-doped sawtooth penta-graphene nanoribbons (N:SSPGNRs) was studied using first-principles methods. Basing our study on density functional theory (DFT), we investigated adsorption configurations, adsorption energy, charge transfer, and the electronic properties of CO-, CO2 - and NH3- adsorbed ontoN:SSPGNRs. We found that CO and CO2 are chemisorbed on the edge of N:SSPGNR, while NH3 is physisorbed. Current-voltage (I–V) characteristics were also investigated using the non-equilibrium Green’s function (NEGF) approach. Gas molecules can modify the current of a device based on N:SSPGNRs. The results indicate the potential of using N:SSPGNRs for detection of these toxic gas molecules.

scholarly journals Modeling of electrotransport properties of Li-intercalated graphene film

2021 ◽  
Vol 2140 (1) ◽  
pp. 012025
Author(s):  
D Sergeyev ◽  
A Duisenova ◽  
Zh Embergenov
Keyword(s):  
Negative Differential Resistance ◽  
Density Functional ◽  
Graphene Film ◽  
Differential Resistance ◽  
Maximum Amount ◽  
Differential Conductivity ◽  
Functional Theory ◽  
Quasiparticle Transport ◽  
Current Voltage ◽  
Current Voltage Characteristics

Abstract In this work, within the framework of density functional theory combined with the method of nonequilibrium Green’s functions the density of states, transmission spectrum, current-voltage characteristics, and differential conductivity of Li-intercalated graphene (LiC6) have been determined. It is shown that in the energy range of -1.3÷-1.05 eV the quasiparticle transport through the nanostructure is disable. The features of IV- and dI/dV-characteristics of LiC6 in the form of decreasing of resistance in the range of -0.4÷0.4 V were revealed, and in the interval of 0.4÷1.4 V formation of negative differential resistance area, related to scattering of quasiparticles. It is established, that LiC6 nanodevice has 12÷13 ballistic channels and has the maximum amount of conductance 12÷13G0 , where Go is the conductance quantum.

scholarly journals Single-crystalline epitaxial TiO film: A metal and superconductor, similar to Ti metal

2021 ◽  
Vol 7 (2) ◽  
pp. eabd4248
Author(s):  
Fengmiao Li ◽  
Yuting Zou ◽  
Myung-Geun Han ◽  
Kateryna Foyevtsova ◽  
Hyungki Shin ◽  
...  
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Tight Binding ◽  
Crystal Form ◽  
Titanium Monoxide ◽  
Binding Model ◽  
Functional Theory ◽  
Single Crystalline ◽  
First Time ◽  
Lattice Matched

Titanium monoxide (TiO), an important member of the rock salt 3d transition-metal monoxides, has not been studied in the stoichiometric single-crystal form. It has been challenging to prepare stoichiometric TiO due to the highly reactive Ti2+. We adapt a closely lattice-matched MgO(001) substrate and report the successful growth of single-crystalline TiO(001) film using molecular beam epitaxy. This enables a first-time study of stoichiometric TiO thin films, showing that TiO is metal but in proximity to Mott insulating state. We observe a transition to the superconducting phase below 0.5 K close to that of Ti metal. Density functional theory (DFT) and a DFT-based tight-binding model demonstrate the extreme importance of direct Ti–Ti bonding in TiO, suggesting that similar superconductivity exists in TiO and Ti metal. Our work introduces the new concept that TiO behaves more similar to its metal counterpart, distinguishing it from other 3d transition-metal monoxides.

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