Related Experiment Video
Updated: Jun 17, 2026
11:42
Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Polarization-induced switching effect in graphene nanoribbon edge-defect junction
1Department of Physics, Fudan University, Shanghai 200433, People's Republic of China.
The Journal of Chemical Physics
|December 23, 2009
Summary
We investigated graphene nanoribbon (GNR) junctions using advanced computational methods. Our findings reveal that transverse electric fields can precisely control the tunneling current in these GNR devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Computational Chemistry
Background:
- Graphene nanoribbons (GNRs) are promising materials for future electronic devices.
- Understanding their transport properties is crucial for device design.
- Self-consistent ab initio calculations are essential for accurate predictions.
Purpose of the Study:
- To investigate the transport properties of graphene nanoribbon (GNR) junctions.
- To model zigzag GNR (ZGNR) electrodes using tight-binding approximation.
- To analyze the impact of edge defects and electric fields on GNR transport.
Main Methods:
- Nonequilibrium Green's function (NEGF) approach.
- Density functional theory (DFT) for ab initio calculations.
- Tight-binding approximation for ZGNR modeling.
- Comparison with GAUSSIAN03 calculations for validation.
Main Results:
- Self-consistent calculations of GNR junction transport properties.
- Explanation of abnormal jump points in transmission spectra using ZGNR band structure.
- Demonstration of tunable tunneling current in edge-defect ZGNR junctions.
- Sensitive control of current via transverse electric fields.
Conclusions:
- The NEGF-DFT approach accurately models GNR junction transport.
- ZGNR band structure explains transmission spectrum anomalies.
- Transverse electric fields offer a method for controlling GNR device currents.
Related Concept Videos
01:16Biasing of P-N Junction
The operation of a p-n junction diode involves various biasing conditions, including forward bias, reverse bias, and equilibrium.
In equilibrium, no external voltage is applied across the p-n junction. The depletion region is formed at the junction interface due to the diffusion of carriers, which leaves behind charged dopants, acceptors on the p-side, and donors on the n-side. These immobile charges create an electric field that prevents further diffusion of carriers. The related energy band...
In equilibrium, no external voltage is applied across the p-n junction. The depletion region is formed at the junction interface due to the diffusion of carriers, which leaves behind charged dopants, acceptors on the p-side, and donors on the n-side. These immobile charges create an electric field that prevents further diffusion of carriers. The related energy band...
01:27Biasing of Metal-Semiconductor Junctions
Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
01:31Dielectric Polarization in a Capacitor
The presence of a dielectric medium in a capacitor not only changes the voltage and capacitance but also affects the electric field. In general, dielectrics can be of two types: polar and nonpolar. In a polar dielectric, the positive and negative charges in the molecules are separated by a distance and hence have a permanent dipole moment. In contrast, no such charge separation exists in a nonpolar dielectric, however the nonpolar molecules get polarized in the presence of an external electric...
01:24Metal-Semiconductor Junctions
The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
01:11P-N junction
A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...
01:22MOSFET: Enhancement Mode
Enhancement-mode MOSFETs are pivotal components in electronics, distinguished by their capacity to act as highly efficient switches. They are part of the larger family of metal-oxide Semiconductor Field-Effect Transistors (MOSFETs). They are available in two types: p-channel and n-channel, each tailored to specific polarity operations.
In their basic form, enhancement-mode MOSFETs are typically non-conductive when the gate-source voltage (Vgs) is zero. This default 'off' state means no current...
In their basic form, enhancement-mode MOSFETs are typically non-conductive when the gate-source voltage (Vgs) is zero. This default 'off' state means no current...