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188 results on '"Gao, Zhengxiang"'

1. Tunable band gap in germanene by surface adsorption

Author

Ye, Meng, Quhe, Ruge, Zheng, Jiaxin, Ni, Zeyuan, Wang, Yangyang, Yuan, Yakun, Tse, Geoffrey, Shi, Junjie, Gao, Zhengxiang, and Lu, Jing

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

Opening a sizable band gap in the zero-gap germanene without heavy loss of carrier mobility is a key issue for its application in nanoelectronic devices such as high-performance field effect transistors (FETs) operating at room temperature. Using the first-principles calculations, we find a band gap is opened at the Dirac point in germanene by single-side adsorption of alkali metal (AM) atoms. This band gap is tunable by varying the coverage and the species of AM atoms, ranging from 0.02 to 0.31 eV, and the maximum global band gap is 0.26 eV. Since the effective masses of electrons and holes in germanene near the Dirac point after surface adsorption (ranging from 0.005 to 0.106 me) are small, the carrier mobility is expected not to degrade much. Therefore germanene is a potential candidate of effective FET channel operating at room temperature upon surface adsorption., Comment: 17 pages, 6 figures

Published
2013
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2. Tunable band gap in few-layer graphene by surface adsorption

Author

Quhe, Ruge, Ma, Jianhua, Zeng, Zesheng, Tang, Kechao, Zheng, Jiaxin, Wang, Yangyang, Ni, Zeyuan, Wang, Lu, Gao, Zhengxiang, Shi, Junjie, and Lu, Jing

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

There is a tunable band gap in ABC-stacked few-layer graphene (FLG) via applying a vertical electric field, but the operation of FLG-based field effect transistor (FET) requires two gates to create a band gap and tune channel's conductance individually. Using first principle calculations, we propose an alternative scheme to open a band gap in ABC-stacked FLG namely via single-side adsorption. The band gap is generally proportional to the charge transfer density. The capability to open a band gap of metal adsorption decreases in this order: K/Al > Cu/Ag/Au > Pt. Moreover, we find that even the band gap of ABA-stacked FLG can be opened if the bond symmetry is broken. Finally, a single-gated FET based on Cu-adsorbed ABC-stacked trilayer graphene is simulated. A clear transmission gap is observed, which is comparable with the band gap. This renders metal-adsorbed FLG a promising channel in a single-gated FET device.

Published
2013

3. Half-Metallic Silicene and Germanene Nanoribbons: towards High-Performance Spintronics Device

Author

Wang, Yangyang, Zheng, Jiaxin, Ni, Zeyuan, Fei, Ruixiang, Liu, Qihang, Quhe, Ruge, Xu, Chengyong, Zhou, Jing, Gao, Zhengxiang, and Lu, Jing

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

By using first-principles calculations, we predict that an in-plane homogenous electrical field can induce half-metallicity in hydrogen-terminated zigzag silicene and germanene nanoribbons (ZSiNRs and ZGeNRs). A dual-gated finite ZSiNR device reveals a nearly perfect spin-filter efficiency of up to 99% while a quadruple-gated finite ZSiNR device serves as an effective spin field effect transistor (FET) with an on/off current ratio of over 100 from ab initio quantum transport simulation. This discovery opens up novel prospect of silicene and germanene in spintronics.

Published
2013
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4. Interfacial Properties of Bilayer and Trilayer Graphene on Metal Substrates

Author

Zheng, Jiaxin, Wang, Yangyang, Wang, Lu, Quhe, Ruge, Ni, Zeyuan, Mei, Wai-Ning, Gao, Zhengxiang, Yu, Dapeng, Shi, Junjie, and Lu, Jing

Subjects
Condensed Matter - Materials Science
Abstract

One popular approach to prepare graphene is to grow them on transition metal substrates via chemical vapor deposition. By using the density functional theory with dispersion correction, we systematically investigate for the first time the interfacial properties of bilayer (BLG) and trilayer graphene (TLG) on metal substrates. Three categories of interfacial structures are revealed. The adsorption of B(T)LG on Al, Ag, Cu, Au, and Pt substrates is a weak physisorption, but a band gap can be opened. The adsorption of B(T)LG on Ti, Ni, and Co substrates is a strong chemisorption, and a stacking-insensitive band gap is opened for the two uncontacted layers of TLG. The adsorption of B(T)LG on Pd substrate is a weaker chemisorption, with a band gap opened for the uncontacted layers. This fundamental study also helps for B(T)LG device study due to inevitable graphene/metal contact., Comment: 1 table, 8 figures

Published
2013
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5. Functionalized Graphene for High Performance Two-dimensional Spintronics Devices

Author

Li, Linze, Qin, Rui, Li, Hong, Yu, Lili, Liu, Qihang, Luo, Guangfu, Lu, Jing, and Gao, Zhengxiang

Subjects
Condensed Matter - Materials Science
Abstract

Using first-principles calculations, we explore the possibility of functionalized graphene as high performance two-dimensional spintronics device. Graphene functionalized with O on one side and H on the other side in the chair conformation is found to be a ferromagnetic metal with a spin-filter efficiency up to 85% at finite bias. The ground state of graphene semi-functionalized with F in the chair conformation is an antiferromagnetic semiconductor, and we construct a magnetoresistive device from it by introducing a magnetic field to stabilize its ferromagnetic metallic state. The resulting room-temperature magnetoresistance is up to 5400%, which is one order of magnitude larger than the available experimental values.

Published
2010

23. Tunable band gap in germanene by surface adsorption

Author

Ye, Meng, primary, Quhe, Ruge, additional, Zheng, Jiaxin, additional, Ni, Zeyuan, additional, Wang, Yangyang, additional, Yuan, Yakun, additional, Tse, Geoffrey, additional, Shi, Junjie, additional, Gao, Zhengxiang, additional, and Lu, Jing, additional

Published
2014
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24. Electronic and transport properties of a biased multilayer hexagonal boron nitride

Author

Tang, K., Ni, Z.Y., Liu, Qihang, Quhe, Ruge, Zheng, Qiye, Zheng, Jiaxin, Fei, R.X., Gao, Zhengxiang, Lu, Jing, Tang, K., Ni, Z.Y., Liu, Qihang, Quhe, Ruge, Zheng, Qiye, Zheng, Jiaxin, Fei, R.X., Gao, Zhengxiang, and Lu, Jing

Abstract

We explore the electronic and transport properties out of a biased multilayer hexagonal boron nitride (h-BN) by first-principles calculations. The band gaps of multilayer h-BN decrease almost linearly with increasing perpendicular electric field, irrespective of the layer number N and stacking manner. The critical electric filed (E 0) required to close the band gap decreases with the increasing N and can be approximated by E 0 = 3.2 / (N − 1) (eV). We provide a quantum transport simulation of a dual-gated 4-layer h-BN with graphene electrodes. The transmission gap in this device can be effectively reduced by double gates, and a high on-off ratio of 3000 is obtained with relatively low voltage. This renders biased MLh-BN a promising channel in field effect transistor fabrication.

Published
2012

25. Structural and electronic properties of bilayer and trilayer graphdiyne

Author

Zheng, Qiye, Luo, Guangfu, Liu, Qihang, Quhe, Ruge, Zheng, Jiaxin, Tang, Kechao, Gao, Zhengxiang, Nagase, Shigeru, Lu, Jing, Zheng, Qiye, Luo, Guangfu, Liu, Qihang, Quhe, Ruge, Zheng, Jiaxin, Tang, Kechao, Gao, Zhengxiang, Nagase, Shigeru, and Lu, Jing

Abstract

Stimulated by the recent experimental synthesis of a new layered carbon allotrope–graphdiyne film, we provide the first systematic ab initio investigation of the structural and electronic properties of bilayer and trilayer graphdiyne and explore the possibility of tuning the energy gap via a homogeneous perpendicular electric field. Our results show that the most stable bilayer and trilayer graphdiyne both have their hexagonal carbon rings stacked in a Bernal way (AB and ABA style configuration, respectively). Bilayer graphdiyne with the most and the second most stable stacking arrangements have direct bandgaps of 0.35 eV and 0.14 eV, respectively; trilayer graphdiyne with stable stacking styles have bandgaps of 0.18–0.33 eV. The bandgaps of the semiconducting bilayer and trilayer graphdiyne generally decrease with increasing external vertical electric field, irrespective of the stacking style. Therefore, the possibility of tuning the electronic structure and optical absorption of bilayer and trilayer graphdiyne with an external electric field is suggested.

Published
2012

29. Tunable band gap in few-layer graphene by surface adsorption

Author

Quhe, Ruge, primary, Ma, Jianhua, additional, Zeng, Zesheng, additional, Tang, Kechao, additional, Zheng, Jiaxin, additional, Wang, Yangyang, additional, Ni, Zeyuan, additional, Wang, Lu, additional, Gao, Zhengxiang, additional, Shi, Junjie, additional, and Lu, Jing, additional

Published
2013
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33. Tunable and sizable band gap in silicene by surface adsorption

Author

Quhe, Ruge, primary, Fei, Ruixiang, additional, Liu, Qihang, additional, Zheng, Jiaxin, additional, Li, Hong, additional, Xu, Chengyong, additional, Ni, Zeyuan, additional, Wang, Yangyang, additional, Yu, Dapeng, additional, Gao, Zhengxiang, additional, and Lu, Jing, additional

Published
2012
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40. Tunable Bandgap in Silicene and Germanene

Author

Ni, Zeyuan, primary, Liu, Qihang, additional, Tang, Kechao, additional, Zheng, Jiaxin, additional, Zhou, Jing, additional, Qin, Rui, additional, Gao, Zhengxiang, additional, Yu, Dapeng, additional, and Lu, Jing, additional

Published
2011
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