Investigating enhanced thermoelectric performance of graphene-based nano-structures.

Recently, it has been demonstrated that graphene nano-ribbons (GNRs) exhibit superior thermoelectric performance compared to graphene sheets. However, the underlying mechanism behind this enhancement has not been systematically investigated and significant opportunity remains for further enhancement of the thermoelectric performance of GNRs by optimizing their charge carrier concentration. In this work, we modulate the carrier concentration of graphene-based nano-structures using a gate voltage and investigate the resulting carrier-concentration-dependent thermoelectric parameters using the Boltzmann transport equations.

Tuneable graphene nanopores for single biomolecule detection.

Solid-state nanopores are promising candidates for next generation DNA and protein sequencing. However, once fabricated, such devices lack tuneability, which greatly restricts their biosensing capabilities. Here we propose a new class of solid-state graphene-based nanopore devices that exhibit a unique capability of self-tuneability, which is used to control their conductance, tuning it to levels comparable to the changes caused by the translocation of a single biomolecule, and hence, enabling high detection sensitivities.

Highly Effective Conductance Modulation in Planar Silicene Field Effect Devices Due to Buckling.

Silicene is an exciting two-dimensional material that shares many of graphene's electronic properties, but differs in its structural buckling. This buckling allows opening a bandgap in silicene through the application of a perpendicular electric field. Here we show that this buckling also enables highly effective modulation of silicene's conductance by means of an in-plane electric field applied through silicene side gates, which can be realized concurrently within the same silicene monolayer.

High Performance Graphene Nano-ribbon Thermoelectric Devices by Incorporation and Dimensional Tuning of Nanopores.

Thermoelectric properties of Graphene nano-ribbons (GNRs) with nanopores (NPs) are explored for a range of pore dimensions in order to achieve a high performance two-dimensional nano-scale thermoelectric device. We reduce thermal conductivity of GNRs by introducing pores in them in order to enhance their thermoelectric performance. The electrical properties (Seebeck coefficient and conductivity) of the device usually degrade with pore inclusion; however, we tune the pore to its optimal dimension in order to minimize this degradation, enhancing the overall thermoelectric performance (high ZT value) of our device.

Asymmetrically-gated graphene self-switching diodes as negative differential resistance devices.

We present an asymmetrically-gated Graphene Self-Switching Diode (G-SSD) as a new negative differential resistance (NDR) device, and study its transport properties using nonequilibrium Green's function (NEGF) formalism and the Extended Huckel (EH) method. The device exhibits a new NDR mechanism, in which a very small quantum tunnelling current is used to control a much-larger channel conduction current, resulting in a very pronounced NDR effect. This NDR effect occurs at low bias voltages, below 1 V, and results in a very high current peak in the μA range and a high peak-to-valley current ratio (PVCR) of 40.

All-graphene planar self-switching MISFEDs, Metal-Insulator-Semiconductor Field-Effect Diodes.

Graphene normally behaves as a semimetal because it lacks a bandgap, but when it is patterned into nanoribbons a bandgap can be introduced. By varying the width of these nanoribbons this band gap can be tuned from semiconducting to metallic. This property allows metallic and semiconducting regions within a single Graphene monolayer, which can be used in realising two-dimensional (2D) planar Metal-Insulator-Semiconductor field effect devices.