Bandgap engineering of α-Ga2O3 by hydrostatic, uniaxial, and equibiaxial strain

2021 ◽  
Author(s):  
Takahiro Kawamura ◽  
Toru Akiyama
Keyword(s):  
First Principles ◽  
Compressive Strain ◽  
Correction Method ◽  
Wide Bandgap ◽  
Potential Range ◽  
First Principles Calculations ◽  
Bandgap Engineering ◽  
Wide Bandgap Semiconductor ◽  
Lattice Strains ◽  
Maximum Value

Abstract Ga2O3 is a wide bandgap semiconductor and an understanding of its bandgap tunability is required to broaden the potential range of Ga2O3 applications. In this study, the different bandgaps of α-Ga2O3 were calculated by performing first-principles calculations using the pseudopotential self-interaction correction method. The relationships between these bandgaps and the material's hydrostatic, uniaxial, and equibiaxial lattice strains were investigated. The direct and indirect bandgaps of strain-free α-Ga2O3 were 4.89 eV and 4.68 eV, respectively. These bandgap values changed linearly and negatively as a function of the hydrostatic strain. Under the uniaxial and equibiaxial strain conditions, the maximum bandgap appeared under application of a small compressive strain, and the bandgaps decreased symmetrically with increasing compressive and tensile strain around the maximum value.

scholarly journals First principles calculations of the electronic and dielectric properties of λ-Ta2O5

TecnoLógicas ◽  
2018 ◽  
Vol 21 (43) ◽  
pp. 43-52 ◽  
Author(s):  
Camilo Valencia-Balvín ◽  
Santiago Pérez-Walton ◽  
Jorge M. Osorio-Guillén
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Wide Bandgap ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Wide Bandgap Semiconductor ◽  
Exchange Correlation ◽  
Good Agreement

Ta2O5 is a wide-bandgap semiconductor that offers interesting applications in microwavecommunications, mainly related to the manufacture of filters and resonators whosesize is inversely proportional to the dielectric constant of the material. For that reason, inthis work we present a theoretical study, based on density functional theory (using PBEsoland hybrid HSE06 exchange-correlation functionals), of the electronic and dielectricproperties of the orthorhombic model -Ta2O5. We found that this model has a direct gap of2.09 and 3.7 eV with PBEsol and HSE06, respectively. Furthermore, the calculated staticdielectric constant, 51, is in good agreement with the reported values of other phases of thissemiconductor.

scholarly journals Equibiaxial Strained Oxygen Adsorption on Pristine Graphene, Nitrogen/Boron Doped Graphene, and Defected Graphene

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4945
Author(s):  
Li-Hua Qu ◽  
Xiao-Long Fu ◽  
Chong-Gui Zhong ◽  
Peng-Xia Zhou ◽  
Jian-Min Zhang
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Compressive Strain ◽  
Oxygen Adsorption ◽  
Strain Engineering ◽  
Pristine Graphene ◽  
First Principles Calculations ◽  
Boron Doped ◽  
Calculation Results ◽  
Doped Graphene

We report first-principles calculations on the structural, mechanical, and electronic properties of O2 molecule adsorption on different graphenes (including pristine graphene (G–O2), N(nitrogen)/B(boron)-doped graphene (G–N/B–O2), and defective graphene (G–D–O2)) under equibiaxial strain. Our calculation results reveal that G–D–O2 possesses the highest binding energy, indicating that it owns the highest stability. Moreover, the stabilities of the four structures are enhanced enormously by the compressive strain larger than 2%. In addition, the band gaps of G–O2 and G–D–O2 exhibit direct and indirect transitions. Our work aims to control the graphene-based structure and electronic properties via strain engineering, which will provide implications for the application of new elastic semiconductor devices.

scholarly journals Metal–insulator-like transition, superconducting dome and topological electronic structure in Ga-doped Re3Ge7

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Yanwei Cui ◽  
Siqi Wu ◽  
Qinqing Zhu ◽  
Guorui Xiao ◽  
Bin Liu ◽  
...  
Keyword(s):  
Phase Transition ◽  
First Principles ◽  
Hole Doping ◽  
First Principles Calculations ◽  
Metal Insulator ◽  
Topological Materials ◽  
Maximum Value ◽  
Fermi Surface Nesting ◽  
Ga Doping ◽  
Rare Opportunity

AbstractSuperconductivity frequently appears by doping compounds that show a collective phase transition. So far, however, this has not been observed in topological materials. Here we report the discovery of superconductivity induced by Ga doping in orthorhombic Re3Ge7, which undergoes a second-order metal–insulator-like transition at ~58 K and is predicted to have a nontrivial band topology. It is found that the substitution of Ga for Ge leads to hole doping in Re3Ge7−xGax. As a consequence, the phase transition is gradually suppressed and disappears above x = 0.2. At this x value, superconductivity emerges and Tc exhibits a dome-like doping dependence with a maximum value of 3.37 K at x = 0.25. First principles calculations suggest that the phase transition in Re3Ge7 is associated with an electronic instability driven by Fermi-surface nesting and the nontrival band topology is preserved after Ga doping. Our results indicate that Ga-doped Re3Ge7 provides a rare opportunity to study the interplay between superconductivity and competing electronic states in a topologically nontrivial system.

scholarly journals Impurity Doping in Mg(OH)2 for n-Type and p-Type Conductivity Control

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2972
Author(s):  
Masaya Ichimura
Keyword(s):  
First Principles ◽  
Energy Levels ◽  
Wide Bandgap ◽  
First Principles Calculations ◽  
Substitutional Site ◽  
Shallow Acceptor ◽  
Impurity Doping ◽  
Trivalent Cations ◽  
Valence Control ◽  
P Type

Magnesium hydroxide (Mg(OH)2) has a wide bandgap of about 5.7 eV and is usually considered an insulator. In this study, the energy levels of impurities introduced into Mg(OH)2 are predicted by first-principles calculations. A supercell of brucite Mg(OH)2 consisting of 135 atoms is used for the calculations, and an impurity atom is introduced either at the substitutional site replacing Mg or the interlayer site. The characteristics of impurity levels are predicted from density-of-states analysis for the charge-neutral cell. According to the results, possible shallow donors are trivalent cations at the substitutional site (e.g., Al and Fe) and cation atoms at the interlayer site (Cu, Ag, Na, and K). On the other hand, an interlayer F atom can be a shallow acceptor. Thus, valence control by impurity doping can turn Mg(OH)2 into a wide-gap semiconductor useful for electronics applications.

Mechanical, electronic and optical properties of bulk and monolayer GeSe2

2020 ◽  
Vol 34 (06) ◽  
pp. 2050034
Author(s):  
Congcong Zeng ◽  
Ru Zhang ◽  
Liyuan Wu ◽  
Qian Wang ◽  
Xi Chen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
First Principles ◽  
Short Wave ◽  
Wide Bandgap ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Wave Region ◽  
Bulk Structure ◽  
Short Wave Region

[Formula: see text], a semiconductor with wide bandgap, has attracted wide attention due to its excellent workability in the short-wave region. Here, we reported the mechanical, electronic and optical properties of bulk and monolayer [Formula: see text] by using first-principles calculations. Our results show that both Young’s modulus and Poisson’s ratio of the monolayer [Formula: see text] exhibit anisotropic behaviors. From the bulk to the monolayer structure, the direct bandgap increases from 2.496 eV to 3.030 eV. Compared to the bulk structure, the monolayer [Formula: see text] exhibits the small average effective mass and significant anisotropy in optical absorption, indicating potential optoelectronic applications.

Theoretical study of stability and electronic structure of the new type of ferroelectric materials XSnO3 (X = Mn, Zn, Fe, Mg)

2014 ◽  
Vol 28 (31) ◽  
pp. 1450224 ◽  
Author(s):  
Wei-Ling Zhu ◽  
Xing-Yuan Chen ◽  
Yu-Jun Zhao ◽  
Tian-Shu Lai
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Chemical Potential ◽  
Theoretical Study ◽  
Ferroelectric Materials ◽  
Potential Range ◽  
First Principles Calculations ◽  
Equilibrium Conditions ◽  
New Type ◽  
Structure Calculations

Based on first-principles calculations and thermodynamic stability analysis, we find that MnSnO 3 and MgSnO 3 could be synthesized under restricted condition, as their bulk phases are stable in a limited chemical potential range with respect to the competing phases. It is also found that FeSnO 3 and ZnSnO 3 are unstable under thermodynamic equilibrium conditions. Electronic structure calculations suggest that the hybridization between TM (transition metal) and O could play important roles for magnetoelectric properties in the XSnO 3 (X = Mn, Zn, Fe), while the hybridization between Sn and O dominates in MgSnO 3.

scholarly journals Strain-Induced Tunable Band Offsets in Blue Phosphorus and WSe2 van der Waals Heterostructure

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 470
Author(s):  
Lingxia Zhang ◽  
Le Huang ◽  
Tao Yin ◽  
Yibin Yang
Keyword(s):  
First Principles ◽  
Compressive Strain ◽  
Van Der Waals ◽  
Spatial Separation ◽  
Band Alignment ◽  
Type Ii ◽  
First Principles Calculations ◽  
Band Offsets ◽  
Van Der Waals Heterostructure ◽  
Vdw Heterostructure

The electronic structure and band offsets of blue phosphorus/WSe2 van der Waals (vdW) heterostructure are investigated via performing first-principles calculations. Blue phosphorus/WSe2 vdW heterostructure exhibits modulation of bandgaps by the applied vertical compressive strain, and a large compressive strain of more than 23% leads to a semiconductor-to-metal transition. Blue phosphorus/WSe2 vdW heterostructure is demonstrated to have a type-II band alignment, which promotes the spontaneous spatial separation of photo-excited electrons and holes. Furthermore, electrons concentrating in BlueP and holes in WSe2 can be enhanced by applied compressive strain, resulting in an increase of carrier concentration. Therefore, these properties make blue phosphorus/WSe2 vdW heterostructure a good candidate for future applications in photodetection.

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