Graphene Adsorbed on Corundum Surface: Clean Interface and Band Gap Opening

2012 ◽  
Vol 1407 ◽  
Author(s):  
Bing Huang ◽  
Qiang Xu ◽  
Su-Huai Wei
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Gate Dielectric ◽  
Dielectric Material ◽  
First Principles Calculations ◽  
Structural And Electronic Properties ◽  
Gap Opening ◽  
Clean Interface ◽  
Injection Barrier ◽  
Gate Dielectric Material

ABSTRACTUsing advanced first-principles calculations, we have studied the structural and electronic properties of graphene/α-Al2O3 interfaces and show that α -Al2O3 is an ideal gate dielectric material for graphene transistors. Clean interface exists between graphene and Al-terminated (or hydroxylated) Al2O3 and the valence band offsets for these systems are large enough to create injection barrier. Remarkably, a band gap of ~180 meV can be induced in graphene layer adsorbed on Al-terminated surface, which is significantly larger than graphene on other popular substrates.

Structure and electronic properties of C2N/graphene predicted by first-principles calculations

RSC Advances ◽  
2016 ◽  
Vol 6 (34) ◽  
pp. 28484-28488 ◽  
Author(s):  
Dandan Wang ◽  
DongXue Han ◽  
Lei Liu ◽  
Li Niu
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Water Splitting ◽  
First Principles ◽  
First Principles Calculations ◽  
Gap Opening

Graphene band gap opening is achieved when integrated with C2N. C2N/graphene heterostructures are promising materials for FETs and water splitting.

COMPARATIVE STUDY OF THE STRUCTURAL AND ELECTRONIC PROPERTIES OF BN(5, 5) AND C(5, 5) NANOTUBES UNDER PRESSURE

2010 ◽  
Vol 24 (24) ◽  
pp. 4851-4859
Author(s):  
KAIHUA HE ◽  
GUANG ZHENG ◽  
GANG CHEN ◽  
QILI CHEN ◽  
MIAO WAN ◽  
...  
Keyword(s):  
High Pressure ◽  
Comparative Study ◽  
Charge Density ◽  
Band Gap ◽  
Electronic Properties ◽  
Cross Section ◽  
First Principles ◽  
First Principles Calculations ◽  
Zinc Blende ◽  
Structural And Electronic Properties

The structural and electronic properties of BN(5, 5) and C(5, 5) nanotubes under pressure are studied by using first principles calculations. In our study range, BN(5, 5) undergoes obvious elliptical distortion, while for C(5, 5) the cross section first becomes an ellipse and then, under further pressure, is flattened. The band gap of BN(5, 5) decreases with increasing pressure, which is inverse to that of zinc blende BN, whereas for C(5, 5) the metallicity is always preserved under high pressure. The population of charge density indicates that intertube bonding is formed under pressure. We also find that BN(5, 5) may collapse, and a new polymer material based on C(5, 5) is formed by applying pressure.

FIRST-PRINCIPLES CALCULATIONS FOR THE STRUCTURAL AND ELECTRONIC PROPERTIES OF ScxAl1-xN ALLOYS

2013 ◽  
Vol 24 (10) ◽  
pp. 1350074 ◽  
Author(s):  
REZEK MOHAMMAD ◽  
ŞENAY KATIRCIOĞLU
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Rock Salt ◽  
First Principles ◽  
First Principles Calculations ◽  
Electronic Band ◽  
Direct Band Gap ◽  
Near Ultraviolet ◽  
Structural And Electronic Properties ◽  
Direct Band

The first-principles calculations based on Density Functional Theory (DFT) within generalized gradient approximation (GGA) of Engel–Vosko–Perdew–Wang and modified exact exchange potential of Becke–Johnson have been introduced for the structural and electronic properties of the Sc x Al 1-x N alloys, respectively. The present lattice constants calculated for the ScAlN alloys and the end compounds ( AlN and ScN ) are found to be in very good agreement with the available experimental and theoretical ones. The stable ground state structures of the Sc x Al 1-x N alloys are determined to be wurtzite for the Sc concentration less than ~0.403 and rock-salt for the higher Sc concentrations. The present electronic band structure calculations within Becke–Johnson scheme are found to be capable of providing energy band gaps of the AlN and ScN compounds very close to the ones of the available experiments and expensive calculations. According to the calculations of Becke–Johnson potential, the Sc x Al 1-x N alloys in the wurtzite and zinc-blende structures are direct band gap materials for the Sc concentrations in the ranges of (0.056 ≤ x ≤ 0.833) and (0.03125 ≤ x ≤ 0.0625, 0.375 ≤ x ≤ 0.96875), respectively. However, the ScAlN alloys in the rock-salt phase are determined to be direct band gap materials for total range of the Sc concentration considered in this work. While the energy gaps of the RS- AlScN alloys are found to be extending from near ultraviolet to near infrared with a large (negative) bowing, the ones of the WZ- AlScN and ZB- AlScN alloys are determined to be varying in a small energy range around near ultraviolet with a small (negative) bowing.

Strain-induced semimetal-to-semiconductor transition and indirect-to-direct band gap transition in monolayer 1T-TiS2

RSC Advances ◽  
2015 ◽  
Vol 5 (102) ◽  
pp. 83876-83879 ◽  
Author(s):  
Chengyong Xu ◽  
Paul A. Brown ◽  
Kevin L. Shuford
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Plane Strain ◽  
Material Properties ◽  
First Principles ◽  
Tensile Strain ◽  
First Principles Calculations ◽  
Direct Band Gap ◽  
Direct Band ◽  
Uniform Plane

We have investigated the effect of uniform plane strain on the electronic properties of monolayer 1T-TiS2using first-principles calculations. With the appropriate tensile strain, the material properties can be transformed from a semimetal to a direct band gap semiconductor.

scholarly journals First-Principles Study on the Stabilities, Electronic and Optical Properties of GexSn1-xSe Alloys

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 876 ◽  
Author(s):  
Qi Qian ◽  
Lei Peng ◽  
Yu Cui ◽  
Liping Sun ◽  
Jinyan Du ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solar Cells ◽  
Band Gap ◽  
Electronic Properties ◽  
First Principles ◽  
Future Application ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Direct Bandgap ◽  
The Future

We systematically study, by using first-principles calculations, stabilities, electronic properties, and optical properties of GexSn1-xSe alloy made of SnSe and GeSe monolayers with different Ge concentrations x = 0.0, 0.25, 0.5, 0.75, and 1.0. Our results show that the critical solubility temperature of the alloy is around 580 K. With the increase of Ge concentration, band gap of the alloy increases nonlinearly and ranges from 0.92 to 1.13 eV at the PBE level and 1.39 to 1.59 eV at the HSE06 level. When the Ge concentration x is more than 0.5, the alloy changes into a direct bandgap semiconductor; the band gap ranges from 1.06 to 1.13 eV at the PBE level and 1.50 to 1.59 eV at the HSE06 level, which falls within the range of the optimum band gap for solar cells. Further optical calculations verify that, through alloying, the optical properties can be improved by subtle controlling the compositions. Since GexSn1-xSe alloys with different compositions have been successfully fabricated in experiments, we hope these insights will contribute to the future application in optoelectronics.

First-Principles Calculations of Titanium Dopants in Alumina

2005 ◽  
Vol 475-479 ◽  
pp. 3095-3098
Author(s):  
Katsuyuki Matsunaga ◽  
Teruyasu Mizoguchi ◽  
Atsutomo Nakamura ◽  
Takahisa Yamamoto ◽  
Yuichi Ikuhara
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Electronic Structures ◽  
First Principles Calculations ◽  
Pseudopotential Calculations ◽  
Formation Energies

First-principles pseudopotential calculations were performed to investigate atomic and electronic structures of titanium (Ti) dopants in alumina (Al2O3). It was found that a substitutional Ti3+ defect induced an extra level occupied by one electron within the band gap of Al2O3. When two or more substitutional Ti3+ defects were located closely to each other, the defect-induced levels exhibited strong bonding interactions, and their formation energies decreased with increasing numbers of Ti3+ defects. This indicates that association and clustering of substitutional Ti3+ defects in Al2O3 can take place due to the interaction of the defect-induced levels.

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