Electronic properties of monolayer silicon carbide nanoribbons using tight-binding approach

Chuan, M.W.,Wong, Y.B.,Hamzah, A.,Alias, N.E.,Sultan, S. Mohamed,Lim, C.S.,Tan, M.L.P. Techno-Press 2022 Advances in nano research Vol.12 No.2

Silicon carbide (SiC) is a binary carbon-silicon compound. In its two-dimensional form, monolayer SiC is composed of a monolayer carbon and silicon atoms constructed as a honeycomb lattice. SiC has recently been receiving increasing attention from researchers owing to its intriguing electronic properties. In this present work, SiC nanoribbons (SiCNRs) are modelled and simulated to obtain accurate electronic properties, which can further guide fabrication processes, through bandgap engineering. The primary objective of this work is to obtain the electronic properties of monolayer SiCNRs by applying numerical computation methods using nearest-neighbour tight-binding models. Hamiltonian operator discretization and approximation of plane wave are assumed for the models and simulation by applying the basis function. The computed electronic properties include the band structures and density of states of monolayer SiCNRs of varying width. Furthermore, the properties are compared with those of graphene nanoribbons. The bandgap of ASiCNR as a function of width are also benchmarked with published DFT-GW and DFT-GGA data. Our nearest neighbour tight-binding (NNTB) model predicted data closer to the calculations based on the standard DFT-GGA and underestimated the bandgap values projected from DFT-GW, which takes in account the exchange-correlation energy of many-body effects.

Elastic and electronic properties of partially ordered and disordered Zr(C₁₋ <i> _x </i>N<i> _x </i>) solid solution compounds: A first principles calculation study

Kim, Jiwoong,Kwon, Hanjung,Kim, Jae-Hee,Roh, Ki-Min,Shin, Doyun,Jang, Hee Dong Elsevier 2015 Journal of Alloys and Compounds Vol.619 No.-

<P><B>Abstract</B></P> <P>The elastic properties and electronic structures of partially ordered and disordered Zr(C<SUB>1−</SUB> <I> <SUB>x</SUB> </I>N<I> <SUB>x</SUB> </I>) solid solution compounds were investigated using first principles calculations to understand the effects of nitrogen content and atomic distribution. To obtain a proper exchange–correlation energy, we used local density and generalized gradient approximations with Perdew–Burke–Ernzerhof (LDA and GGA-PBE) parametrization. Partially ordered and disordered structures of Zr(C<SUB>1−</SUB> <I> <SUB>x</SUB> </I>N<I> <SUB>x</SUB> </I>) compounds were expressed using unit cell and special quasi-random structure (SQS) models, respectively. We demonstrated that although the disordered models have P1 symmetry with different model sizes and cell shapes compared with ordered models, they reproduce the equilibrium structure and elastic properties of the Zr(C<SUB>1−</SUB> <I> <SUB>x</SUB> </I>N<I> <SUB>x</SUB> </I>) compounds with B1 (Fm-3m) symmetry. However, clear differences exist in the electronic structures. Therefore, the atomic configuration is essential for calculating the electronic structures of the Zr(C<SUB>1−</SUB> <I> <SUB>x</SUB> </I>N<I> <SUB>x</SUB> </I>) compounds.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Elastic and electronic properties of Zr(C<SUB>1−<I>x</I> </SUB>N<SUB> <I>x</I> </SUB>) compounds by first principles. </LI> <LI> We elucidate the effects of atomic configuration on compound properties. </LI> <LI> Ordered and disordered models are depicted by unit cell and special quasi-random structures. </LI> <LI> Disordered structures are suitable models to estimate compound elastic properties. </LI> <LI> The atomic configuration is essential to obtain accurate electronic structures. </LI> </UL> </P>

Structural optimization for thermoelectric properties in Cu-Bi-S pavonite compounds

Hwang, Jae-Yeol,Ahn, Jun Yeon,Lee, Kyu Hyoung,Kim, Sung Wng Elsevier 2017 Journal of Alloys and Compounds Vol.704 No.-

<P><B>Abstract</B></P> <P>We report the enhancement of thermoelectric properties in the complex structured Cu-Bi-S pavonite compounds by optimizing the structural configuration through tuning the Bi-site occupancy, and substitutional doping at interstitial Cu sites by Zn. We verify that electronic transport properties depend on the structural deformation by the Bi site occupancy. Furthermore, we demonstrate that the modification of interstitial site ions enables selective control of thermal conductivity and intrinsically low thermal conductivity can be further suppressed by structural optimization without deteriorating electronic transport properties. We propose that understanding of crystal structure as a basic strategy permits the optimization of thermoelectric properties in the complex structures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Strong correlation between structure and thermoelectric properties in Cu-Bi-S compounds. </LI> <LI> Electronic transport properties depend on the structural deformation by the Bi site occupancy. </LI> <LI> The modification of interstitial site ions enables selective control of thermal conductivity. </LI> <LI> Intrinsically low thermal conductivity can be further suppressed by structural optimization. </LI> <LI> Understanding of structure as a basic strategy for the optimization of thermoelectric properties. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Edge perturbation on electronic properties of boron nitride nanoribbons

K.L. Wong,K.W. Lai,M.W. Chuan,Y. Wong,A. Hamzah,S. Rusli,N.E. Alias,S. Mohamed Sultan,C.S. Lim,M.L.P. Tan Techno-Press 2023 Advances in nano research Vol.15 No.5

Hexagonal boron nitride (h-BN), commonly referred to as Boron Nitride Nanoribbons (BNNRs), is an electrical insulator characterized by high thermal stability and a wide bandgap semiconductor property. This study delves into the electronic properties of two BNNR configurations: Armchair BNNRs (ABNNRs) and Zigzag BNNRs (ZBNNRs). Utilizing the nearest-neighbour tight-binding approach and numerical methods, the electronic properties of BNNRs were simulated. A simplifying assumption, the Hamiltonian matrix is used to compute the electronic properties by considering the self-interaction energy of a unit cell and the interaction energy between the unit cells. The edge perturbation is applied to the selected atoms of ABNNRs and ZBNNRs to simulate the electronic properties changes. This simulation work is done by generating a custom script using numerical computational methods in MATLAB software. When benchmarked against a reference study, our results aligned closely in terms of band structure and bandgap energy for ABNNRs. However, variations were observed in the peak values of the continuous curves for the local density of states. This discrepancy can be attributed to the use of numerical methods in our study, in contrast to the semi-analytical approach adopted in the reference work.

First-principles investigation of structural, elastic, electronic and magnetic properties of Be0.75Co0.25Y (Y=S, Se and Te) compounds

W. Tanveer,M.A. Faridi,N.A. Noor,Asif Mahmood,B. Amin 한국물리학회 2015 Current Applied Physics Vol.15 No.11

We have theoretically investigated the structural, elastic, electronic and magnetic properties of Be0.75Co0.25Y (Y=S, Se and Te) alloys, in their zinc-blend phase. This study is carried out by using the fullpotential augmented plane wave plus local orbitals method within the density functional theory. Foe computing the exchange-correlation potential, the Wu and Cohen generalized gradient approximation is employed to calculate structural and elastic properties whereas the modified Becke and Johnson potential local density approximation is utilized to examine electronic and magnetic properties. By minimizing the total energy in paramagnetic (PM) and ferromagnetic (FM) phases, it is found the studied compounds are stable in FM structure. The mechanical behavior of the studied compounds is reported with the calculation of shear modulus, Young's modulus, and Poisson's ratio provides. Such mechanical aspects might be useful for the experimentalists to study the mechanical properties upon alloying BeY compounds with Co. We also compute electronic structures, density of states (total and partial), pdexchange splitting and magnetic moments. Moreover, bond nature is studied by estimating the spin polarized charge densities of Be0.75Co0.25Y (Y=S, Se and Te).

Tunable electronic and optical properties of GaS/GaSe van der Waals heterostructure

Hamad Rahman Jappor,Majeed Ali Habeeb 한국물리학회 2018 Current Applied Physics Vol.18 No.6

We have used first-principles calculations to investigate the electronic and optical properties of GaS/GaSe van der Waals heterostructures formed by stacking two-dimensional GaSe and GaSe monolayers. Our findings confirm that the GaS/GaSe heterostructures transform from an indirect to a direct band gap material for the two stackings considered in this study. In addition, we found that the direct band gaps are 1.780 eV and 1.736 eV for AA and AB stacking, respectively. It is observed that the behavior of the optical properties of AA stacking is similar to AB stacking with some differences in details and both heterostructures located in UV range. The refractive index values are 2.21 (AA pattern) and 2.18 (AB pattern) at zero photon energy limit and increase to 2.937 for AA and 2.18 AB patterns and both located in the visible region. More importantly, the GaS/GaSe heterostructures have a variety of extraordinary electronic and optical properties. Accordingly, these heterostructures can be useful for the solar cell, nanoelectronics, and optoelectronic applications.

Electronic and optical properties of graphane, silicane, MoS2 homo-bilayers and hetero-bilayers

Jia-Qi Hu,Lin-Han Xu,Shun-Qing Wu,Zi-Zhong Zhu 한국물리학회 2019 Current Applied Physics Vol.19 No.11

The electronic and optical properties of graphane, silicane and MoS2 bilayers, as well as the graphane/MoS2 and silicane/MoS2 hetero-bilayers, are calculated by the first-principles method. The interlayer interactions of all the bilayer systems are shown to be mainly van der Waals. Both the graphane/MoS2 and silicane/MoS2 heterobilayers belong to the type-II heterostructure, which can be utilized in photo-voltaic devices due to the efficient spatial separation of electrons and holes. For optical properties, the distinctions for the imaginary parts of the dielectric function 2 ( ) between the monolayer and bilayer systems for both the graphane and silicane are more evident in electric vector E||z. However, the differences between 2 ( ) of the monolayer and bilayer MoS2 materials are more significant in E||x. Broader light absorption ranges of the hetero-bilayers are reached, which can also improve the charge separation of the electron-hole pairs.

Electronic Structure and Optical Properties of a Mn-Doped InSe/WSe2 van der Walls Heterostructure: First Principles Calculations

Liang Rundong,Zhao Xiuwen,Hu Guichao,Yue Weiwei,Yuan Xiaobo,Ren Junfeng 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.7

InSe-based van der Walls heterostructures (vdWHs) have attracted research interests recently because of their particular properties. In this work, the electronic structure and the optical properties of Mn-doped InSe/WSe2 vdWHs are investigated by using first-principles calculations. Mn doping in InSe/WSe2 vdWHs induces an increase in the system's band gap. The optical properties of the vdWHs are also studied, and the absorption intensity of Mn-doped InSe/WSe2 is found to be enhanced in the near-infrared and ultraviolet regions. In addition, built-in electric fields are generated in InSe/WSe2 and Mn-doped InSe/WSe2, which can inhibit recombination of photogenerated electron-hole pairs. This work predicates the feasibility of enhancing the optical properties in InSe/WSe2 vdWHs by introducing dopants, which extends the applications of InSe materials in the field of optoelectronics.

Structural, Optical and Electrical Properties of PVA/PEO/SnO2 New Nanocomposites for Flexible Devices

Aseel Hadi,Ahmed Hashim,Yahya Al-Khafaji 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.3

Fabrication of polyvinyl alcohol (PVA)–polyethylene oxide (PEO) blend doped with tin dioxide (SnO 2 ) nanocomposites has been investigated for flexible electrical and optical applications. The prepared nanocomposites have low cost, lightweight, flexible, high corrosion resistance, good optical and electrical properties. These properties of fabricated nanocomposites make it useful for diff erent optoelectronics applications such as: sensors, solar cells, transistors, diodes, capacitors, energy storage etc. The structural, optical and electrical properties of (PVA–PEO–SnO 2 ) nanocomposites have been studied. The experimental results of optical properties for (PVA–PEO–SnO2) nanocomposites showed that the nanocomposites have higher absorbance in UV region at wavelength range (200–280) nm. This behavior makes the nanocomposites may be used for optoelectronics applications. The absorbance, absorption coeffi cient, extinction coeffi cient, refractive index, real and imaginary dielectric constants and optical conductivity of polymer blend are increased with the increase in SnO2 nanoparticles concentrations while the transmittance and energy band gap are decreased with the increase in SnO2 nanoparticles concentrations. The decrease in energy band gap is useful for diff erent optoelectronics devices industries. Also, the results showed that the dielectric constant and dielectric loss decrease while the conductivity increases with the increase in frequency. The dielectric constant, dielectric loss and conductivity are increased with the increase in SnO2 nanoparticles concentrations. The electrical properties showed that the (PVA–PEO–SnO2) nanocomposites have good dielectric parameters which it may be used for different electronics applications.

Properties of low-temperature nanocomposite Sn-58Bi-Ta2O5 solder for mini LED bonding on flexible electronics

Hyejun Kang,Jang Beak Kim,Gyeong Ah Lee,Sri Harini Rajendran,Jae Pil Jung 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11

Today, high brightness and contrast mini LEDs has a chance to compete with OLED in flexible displays and consumer electronics. Nanocomposite Sn-Bi solders received noticeable attention for flexible electronics due to their improved mechanical properties and low soldering temperature. Meanwhile, brittleness of Bi phase inter-metallic compounds (IMC) accounts to a reliability concern since FET’s may experience mechanical shock upon bending. Addition of NPs in Sn-Bi solder alloy is an efficient way to improve the reliability of the solder joints by reducing the IMC thickness as well as refining the brittle Bi phase The nanocomposite solder in this study contains 0.05 wt%, 0.15 wt%, 0.3 wt% and 0.6 wt% of Ta2O5 nanoparticles in Sn-57.6Bi-0.4Ag solder alloy. In order to investigate the metallurgical and mechanical properties of the nanocomposite solder, the melting point, microstructure, wetting property and tensile test was carried out. The melting point of the developed nanocomposite solder was slightly reduced to about 1~ 2℃ from 139℃, which is the melting point of the Sn-Bi based solder. As for the microstructure, it was confirmed that the size of the β-Sn phase decreased as the amount of Ta2O5 was added, the entire β-Sn phase area decreased, and the microstructure of the solder became fine with the addition of nanoparticles. The wetting force of the solder composite reinforced with nanoparticles was also improved by 0.46 mN compared to the solder without the nanoparticles, and the tensile strength and elongation also showed a tendency to increase through the addition of nanoparticles. In particular, the elongation was improved up to 90% compared to the solder without adding nanoparticles. The developed nanocomposite solder was used to mount an LED chip on a flexible printed circuit board, and the defects, shear strength and electrical resistance were measured to investigate the boding and electrical characteristics. The addition of nanoparticles of solder was improved the bonding properties by reducing the defect rate and increasing the shear strength of the solder alloy. The void ratio of Nanocomposite solder was 2.503% while base solder was 3.03% and shear strength of nanocomposite solder was 65.2 MPa while base solder was 56.4 MPa. Electrical resistance value of the junction with the nanocomposite solder showed only a slight decreasing from the base solder, confirming that the addition of nanoparticles does not affect the electrical properties of the solder.