scholarly journals One-dimensional confinement and width-dependent bandgap formation in epitaxial graphene nanoribbons

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Hrag Karakachian ◽  
T. T. Nhung Nguyen ◽  
Johannes Aprojanz ◽  
Alexei A. Zakharov ◽  
Rositsa Yakimova ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Quantum Confinement ◽  
Field Effect Transistors ◽  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Pristine Graphene ◽  
One Dimensional ◽  
Experimental Findings

AbstractThe ability to define an off state in logic electronics is the key ingredient that is impossible to fulfill using a conventional pristine graphene layer, due to the absence of an electronic bandgap. For years, this property has been the missing element for incorporating graphene into next-generation field effect transistors. In this work, we grow high-quality armchair graphene nanoribbons on the sidewalls of 6H-SiC mesa structures. Angle-resolved photoelectron spectroscopy (ARPES) and scanning tunneling spectroscopy measurements reveal the development of a width-dependent semiconducting gap driven by quantum confinement effects. Furthermore, ARPES demonstrates an ideal one-dimensional electronic behavior that is realized in a graphene-based environment, consisting of well-resolved subbands, dispersing and non-dispersing along and across the ribbons respectively. Our experimental findings, coupled with theoretical tight-binding calculations, set the grounds for a deeper exploration of quantum confinement phenomena and may open intriguing avenues for new low-power electronics.

Chemically Stable Semiconductor Surface Layers Using Low-Temperature Grown GaAs

1996 ◽  
Vol 448 ◽  
Author(s):  
D.B. Janes ◽  
S. Hong ◽  
V. R. Kolagunta ◽  
D. McInturff ◽  
T.-B. NG ◽  
...  
Keyword(s):  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
Field Effect Transistors ◽  
Layer Structure ◽  
Gaas Layer ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Semiconductor Surface ◽  
Low Resistance ◽  
Low Temperature Grown Gaas

AbstractThe chemical stability of a GaAs layer structure consisting of a thin (10 nm) layer of low-temperature-grown GaAs (LTG:GaAs) on a heavily n-doped GaAs layer, both grown by molecular beam epitaxy, is described. Scanning tunneling spectroscopy and X-ray photoelectron spectroscopy performed after atmospheric exposure indicate that the LTG:GaAs surface layer oxidizes much less rapidly than comparable layers of stoichiometric GaAs. There is also evidence that the terminal oxide thickness is smaller than that of stoichiometric GaAs. The spectroscopy results are used to confirm a model for conduction in low resistance, nonalloyed contacts employing comparable layer structures. The inhibited surface oxidation rate is attributed to the bulk Fermi level pinning and the low minority carrier lifetime in unannealed LTG:GaAs. Device applications including low-resistance cap layers for field-effect transistors are described.

scholarly journals Inducing metallicity in graphene nanoribbons via zero-mode superlattices

Science ◽  
2020 ◽  
Vol 369 (6511) ◽  
pp. 1597-1603 ◽  
Author(s):  
Daniel J. Rizzo ◽  
Gregory Veber ◽  
Jingwei Jiang ◽  
Ryan McCurdy ◽  
Ting Cao ◽  
...  
Keyword(s):  
Density Functional ◽  
Zero Mode ◽  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
General Technique ◽  
Electronic Band ◽  
Wide Range ◽  
Recent Developments

The design and fabrication of robust metallic states in graphene nanoribbons (GNRs) are challenging because lateral quantum confinement and many-electron interactions induce electronic band gaps when graphene is patterned at nanometer length scales. Recent developments in bottom-up synthesis have enabled the design and characterization of atomically precise GNRs, but strategies for realizing GNR metallicity have been elusive. Here we demonstrate a general technique for inducing metallicity in GNRs by inserting a symmetric superlattice of zero-energy modes into otherwise semiconducting GNRs. We verify the resulting metallicity using scanning tunneling spectroscopy as well as first-principles density-functional theory and tight-binding calculations. Our results reveal that the metallic bandwidth in GNRs can be tuned over a wide range by controlling the overlap of zero-mode wave functions through intentional sublattice symmetry breaking.

2D Self-assembly and Electronic Characterization of Oxygen-Boron-Oxygen-Doped Chiral Graphene Nanoribbons

2021 ◽  
Author(s):  
Lei Jin ◽  
Nerea Bilbao ◽  
Yang Lv ◽  
Xiao-Ye Wang ◽  
Soltani Paniz ◽  
...  
Keyword(s):  
Edge Effects ◽  
Self Assembly ◽  
Quantum Confinement ◽  
Graphene Nanoribbons ◽  
One Dimensional ◽  
The Past ◽  
Different Types

Graphene nanoribbons (GNRs), quasi-one-dimensional strips of graphene, exhibit a nonzero bandgap due to quantum confinement and edge effects. In the past decade, different types of GNRs with atomically precise structures...

scholarly journals Scalable Majorana vortex modes in iron-based superconductors

2020 ◽  
Vol 6 (9) ◽  
pp. eaay0443 ◽  
Author(s):  
Ching-Kai Chiu ◽  
T. Machida ◽  
Yingyi Huang ◽  
T. Hanaguri ◽  
Fu-Chun Zhang
Keyword(s):  
Tight Binding ◽  
Three Dimensional ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Zero Energy ◽  
Binding Model ◽  
Zero Bias ◽  
Iron Based Superconductors ◽  
Iron Based ◽  
Important Indication

The iron-based superconductor FeTexSe1−x is one of the material candidates hosting Majorana vortex modes residing in the vortex cores. It has been observed by recent scanning tunneling spectroscopy measurement that the fraction of vortex cores having zero-bias peaks decreases with increasing magnetic field on the surface of FeTexSe1−x. The hybridization of two Majorana vortex modes cannot simply explain this phenomenon. We construct a three-dimensional tight-binding model simulating the physics of over a hundred Majorana vortex modes in FeTexSe1−x. Our simulation shows that the Majorana hybridization and disordered vortex distribution can explain the decreasing fraction of the zero-bias peaks observed in the experiment; the statistics of the energy peaks off zero energy in our Majorana simulation are in agreement with the experiment. These agreements lead to an important indication of scalable Majorana vortex modes in FeTexSe1−x. Thus, FeTexSe1−x can be one promising platform having scalable Majorana qubits for quantum computing.

scholarly journals Characterization of Uranium Particles Produced via Pulsed Laser Deposition

2003 ◽  
Vol 802 ◽  
Author(s):  
S. C. Glade ◽  
T. W. Trelenberg ◽  
J. G. Tobin ◽  
A. V. Hamza
Keyword(s):  
Pulsed Laser Deposition ◽  
Photoelectron Spectroscopy ◽  
Pulsed Laser ◽  
Scanning Tunneling Spectroscopy ◽  
Laser Deposition ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Gaseous Species ◽  
Experimental Apparatus

ABSTRACTWe have constructed an experimental apparatus for the synthesis (via pulsed laser deposition) and analysis of nanoparticles and thin films of plutonium and other actinides. In-situ analysis techniques include x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning tunneling microscopy (STM), and scanning tunneling spectroscopy (STS). Also, the oxidation kinetics and the reaction kinetics of actinides with other gaseous species can be studied with this experimental apparatus. Preliminary results on depleted uranium are presented.

scholarly journals Revealing the Electronic Structure of Silicon Intercalated Armchair Graphene Nanoribbons by Scanning Tunneling Spectroscopy

Nano Letters ◽  
2017 ◽  
Vol 17 (4) ◽  
pp. 2197-2203 ◽  
Author(s):  
Okan Deniz ◽  
Carlos Sánchez-Sánchez ◽  
Tim Dumslaff ◽  
Xinliang Feng ◽  
Akimitsu Narita ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Graphene Nanoribbons ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Armchair Graphene Nanoribbons ◽  
Armchair Graphene

Current Status of Graphene Transistors

2009 ◽  
Vol 156-158 ◽  
pp. 499-509 ◽  
Author(s):  
M.C. Lemme
Keyword(s):  
Band Gap ◽  
Quantum Confinement ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Graphene Nanoribbons ◽  
Cmos Technology ◽  
Current Status ◽  
Energy Band Gap ◽  
Layer Graphene ◽  
Silicon Cmos

This paper reviews the current status of graphene transistors as potential supplement to silicon CMOS technology. A short overview of graphene manufacturing and metrology methods is followed by an introduction of macroscopic graphene field effect transistors (FETs). The absence of an energy band gap is shown to result in severe shortcomings for logic applications. Possibilities to engineer a band gap in graphene FETs including quantum confinement in graphene Nanoribbons (GNRs) and electrically or substrate induced asymmetry in double and multi layer graphene are discussed. Novel switching mechanisms in graphene transistors are briefly introduced that could lead to future memory devices. Finally, graphene FETs are shown to be of interest for analog radio frequency applications.

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