scholarly journals Global strain-induced scalar potential in graphene devices

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lujun Wang ◽  
Andreas Baumgartner ◽  
Péter Makk ◽  
Simon Zihlmann ◽  
Blesson Sam Varghese ◽  
...  
Keyword(s):  
Dirac Point ◽  
Direct Evidence ◽  
Electronic Device ◽  
Scalar Potential ◽  
Energy Shift ◽  
Global Strain ◽  
Optical And Electronic Properties ◽  
Similar Materials ◽  
Graphene Devices ◽  
External Strain

AbstractBy mechanically distorting a crystal lattice it is possible to engineer the electronic and optical properties of a material. In graphene, one of the major effects of such a distortion is an energy shift of the Dirac point, often described as a scalar potential. We demonstrate how such a scalar potential can be generated systematically over an entire electronic device and how the resulting changes in the graphene work function can be detected in transport experiments. Combined with Raman spectroscopy, we obtain a characteristic scalar potential consistent with recent theoretical estimates. This direct evidence for a scalar potential on a macroscopic scale due to deterministically generated strain in graphene paves the way for engineering the optical and electronic properties of graphene and similar materials by using external strain.

Reply to: Dirac-point photocurrents due to photothermoelectric effect in non-uniform graphene devices

2020 ◽  
Vol 15 (4) ◽  
pp. 244-246
Author(s):  
Qiong Ma ◽  
Justin C. W. Song ◽  
Nathaniel M. Gabor ◽  
Pablo Jarillo-Herrero
Keyword(s):  
Dirac Point ◽  
Graphene Devices

scholarly journals Positioning of the Fermi Level in Graphene Devices with Asymmetric Metal Electrodes

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Bum-Kyu Kim ◽  
Eun-Kyoung Jeon ◽  
Ju-Jin Kim ◽  
Jeong-O Lee
Keyword(s):  
Fermi Level ◽  
Dirac Point ◽  
Metal Electrode ◽  
Peak Position ◽  
Metal Contacts ◽  
Metal Electrodes ◽  
Hole Band ◽  
Graphene Devices ◽  
Hybrid Devices ◽  
Bias Range

To elucidate the effect of the work function on the position of the Dirac point, we fabricated graphene devices with asymmetric metal contacts. By measuring the peak position of the resistance for each pair of metal electrodes, we obtained the voltage of the Dirac pointVgDirac(V) from the gate response. We found that the position ofVgDirac(V) in the hybrid devices was significantly influenced by the type of metal electrode. The measured shifts inVgDirac(V) were closely related to the modified work functions of the metal-graphene complexes. Within a certain bias range, the Fermi level of one of the contacts aligned with the electron band and that of the other contact aligned with the hole band.

An unconventional method for measuring the TcL3-edge of technetium compounds

2014 ◽  
Vol 21 (6) ◽  
pp. 1275-1281 ◽  
Author(s):  
Peter E. R. Blanchard ◽  
Emily Reynolds ◽  
Brendan J. Kennedy ◽  
Chris D. Ling ◽  
Zhaoming Zhang ◽  
...  
Keyword(s):  
Crystal Field ◽  
Direct Evidence ◽  
Energy Shift ◽  
Energy Difference ◽  
Crystal Field Splitting ◽  
Oxidation States ◽  
Field Splitting ◽  
Absorption Edge Energy ◽  
Powder Samples ◽  
Unconventional Method

TcL3-edge XANES spectra have been collected on powder samples of SrTcO3(octahedral Tc4+) and NH4TcO4(tetrahedral Tc7+) immobilized in an epoxy resin. Features in the TcL3-edge XANES spectra are compared with the pre-edge feature of the TcK-edge as well as other 4dtransition metalL3-edges. Evidence of crystal field splitting is obvious in the TcL3-edge, which is sensitive to the coordination number and oxidation state of the Tc cation. The TcL3absorption edge energy difference between SrTcO3(Tc4+) and NH4TcO4(Tc7+) shows that the energy shift at the TcL3-edge is an effective tool for studying changes in the oxidation states of technetium compounds. The TcL3-edge spectra are compared with those obtained from Mo and Ru oxide standards with various oxidation states and coordination environments. Most importantly, fitting the TcL3-edge to component peaks can provide direct evidence of crystal field splitting that cannot be obtained from the TcK-edge.

Selective n-type doping in graphene via the aluminium nanoparticle decoration approach

2014 ◽  
Vol 2 (27) ◽  
pp. 5417-5421 ◽  
Author(s):  
Xiaoling Shi ◽  
Guofa Dong ◽  
Ming Fang ◽  
Fengyun Wang ◽  
Hao Lin ◽  
...  
Keyword(s):  
Dirac Point ◽  
Effective Technique ◽  
Current Ratio ◽  
Al Nanoparticles ◽  
Left Shift ◽  
Graphene Devices

A simple and effective technique is presented to left shift the Dirac point of graphene transistors to induce n-type doping via the thermal decoration of Al nanoparticles. The versatility of this approach is illustrated by the fabrication of air-stable n-type doping in graphene devices with the improved on/off current ratio.

scholarly journals Ultra-low contact resistance in graphene devices at the Dirac point

2D Materials ◽  
2018 ◽  
Vol 5 (2) ◽  
pp. 025014 ◽  
Author(s):  
Luca Anzi ◽  
Aida Mansouri ◽  
Paolo Pedrinazzi ◽  
Erica Guerriero ◽  
Marco Fiocco ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Dirac Point ◽  
Graphene Devices

scholarly journals Quantum confinement of the Dirac surface states in topological-insulator nanowires

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Felix Münning ◽  
Oliver Breunig ◽  
Henry F. Legg ◽  
Stefan Roitsch ◽  
Dingxun Fan ◽  
...  
Keyword(s):  
Quantum Computing ◽  
Quantum Confinement ◽  
Dirac Point ◽  
Direct Evidence ◽  
Chemical Potential ◽  
Three Dimensional ◽  
Surface States ◽  
Mesoscopic Physics ◽  
Zero Modes ◽  
Topological Quantum

AbstractThe non-trivial topology of three-dimensional topological insulators dictates the appearance of gapless Dirac surface states. Intriguingly, when made into a nanowire, quantum confinement leads to a peculiar gapped Dirac sub-band structure. This gap is useful for, e.g., future Majorana qubits based on TIs. Furthermore, these sub-bands can be manipulated by a magnetic flux and are an ideal platform for generating stable Majorana zero modes, playing a key role in topological quantum computing. However, direct evidence for the Dirac sub-bands in TI nanowires has not been reported so far. Here, using devices fabricated from thin bulk-insulating (Bi1−xSbx)2Te3 nanowires we show that non-equidistant resistance peaks, observed upon gate-tuning the chemical potential across the Dirac point, are the unique signatures of the quantized sub-bands. These TI nanowires open the way to address the topological mesoscopic physics, and eventually the Majorana physics when proximitized by an s-wave superconductor.

Growth and Characterization of 13C Enriched 4H-SiC for Fundamental Materials Studies

2007 ◽  
Vol 556-557 ◽  
pp. 13-16 ◽  
Author(s):  
Yeon Suk Jang ◽  
Sakwe Aloysius Sakwe ◽  
Peter J. Wellmann ◽  
Sandrine Juillaguet ◽  
Hervé Peyre ◽  
...  
Keyword(s):  
Electronic Device ◽  
Energy Shift ◽  
Point Of View ◽  
Bandgap Energy ◽  
Physical Point ◽  
Interstitial Defect ◽  
First Results ◽  
Device Applications

We have carried out the growth and basic characterization of isotopically enriched 4HSi 13C crystals. In recent years the growth of 13C enriched 6H-SiC has been performed in order to carry out fundamental materials studies (e.g. determination of phonon energies, fundamental bandgap shift, carbon interstitial defect study, analysis of the physical vapor transport (PVT) growth process). For electronic device applications, however, the 4H-SiC polytype is the favored material, because it offers greater electron mobility. In this paper we present the growth of 4H-Si13C single crystals with up to 60% of 13C concentration. From a physical point of view we present first results on phonons as well as the fundamental bandgap energy shift due to 13C incorporation into the SiC lattice.

Chemistry at the Dirac Point of Graphene: Diels-Alder Approach to Reversible Band Gap Engineering and High Mobility Graphene Devices

2014 ◽  
Vol 1658 ◽  
Author(s):  
Santanu Sarkar
Keyword(s):  
Band Gap ◽  
Dirac Point ◽  
High Mobility ◽  
Single Layer ◽  
Diels Alder ◽  
Single Layer Graphene ◽  
Dual Nature ◽  
Band Gap Engineering ◽  
Graphene Devices ◽  
Graphene Fet

ABSTRACTThe Diels-Alder (DA) pericyclic chemistry is one of the most powerful reactions in synthetic chemistry. We have recently shown that the unique zero-band-gap electronic structure of graphene at the Dirac point facilitates the band-gap-dependent DA reaction of graphene, although graphene is the thermochemical reference for carbon. We have shown that in the DA reactions, graphene can function either as a diene or a dienophile (dual nature). Such DA functionalization of graphene when applied to graphene-FET devices allows balanced functionalization (creation of a pair of new sp3 centers or divacancies) at both A and B graphene sublattices, allowing the fabrication of high mobility DA-functionalized single-layer graphene devices (DA-SLG) with acceptable on/off ratio. The chemistry is thermally reversible via retro-DA chemistry, thus allowing reversible engineering of graphene devices.

scholarly journals Dirac-point photocurrents due to the photothermoelectric effect in non-uniform graphene devices

2020 ◽  
Vol 15 (4) ◽  
pp. 241-243 ◽  
Author(s):  
Michael S. Fuhrer ◽  
Nikhil V. Medhekar
Keyword(s):  
Dirac Point ◽  
Graphene Devices

Hybrid Zero-Dimensional C60 clusters with Graphene – Synthesis, Fabrication and Transport Characteristics

MRS Advances ◽  
2017 ◽  
Vol 2 (60) ◽  
pp. 3727-3732
Author(s):  
Srishti Chugh ◽  
Luis Echegoyen ◽  
Anupama B. Kaul
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Raman Spectroscopy ◽  
Electronic Device ◽  
Deposition Technique ◽  
Exfoliated Graphene ◽  
Graphene Synthesis ◽  
Before And After ◽  
Graphene Devices ◽  
Scanning Electron

ABSTRACTIn this work, a new method is presented to synthesize graphene-C60 hybrid materials using an electrophoretic deposition technique to study the graphene-C60 interactions. Electronic measurements of the structure were conducted before and after the attachment of C60 clusters at different applied voltages on graphene devices. The assembled clusters of C60 on mechanically exfoliated graphene were investigated using Raman Spectroscopy and Scanning Electron Microscopy (SEM), which reveal a uniform morphology of C60 on graphene. The results indicate that graphene-C60 hybrids are excellent electron accepting/charge transporting materials which can provide an effective route to facilitate the application of these hybrids in electronic or opto-electronic device platforms.

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