Electrical and Electronic Engineering - Research Publications

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    Silicon nanowire photodetector enhanced by a bow-tie antenna
    Felic, GK ; Al-Dirini, F ; Hossain, FM ; Thanh, CN ; Skafidas, E (SPRINGER, 2014-05-01)
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    All-Graphene Planar Self-Switching MISFEDs, Metal-Insulator-Semiconductor Field-Effect Diodes
    Al-Dirini, F ; Hossain, FM ; Nirmalathas, A ; Skafidas, E (NATURE PUBLISHING GROUP, 2014-02-05)
    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. Based on this concept, we present a new class of nano-scale planar devices named Graphene Self-Switching MISFEDs (Metal-Insulator-Semiconductor Field-Effect Diodes), in which Graphene is used as the metal and the semiconductor concurrently. The presented devices exhibit excellent current-voltage characteristics while occupying an ultra-small area with sub-10 nm dimensions and an ultimate thinness of a single atom. Quantum mechanical simulation results, based on the Extended Huckel method and Nonequilibrium Green's Function Formalism, show that a Graphene Self-Switching MISFED with a channel as short as 5 nm can achieve forward-to-reverse current rectification ratios exceeding 5000.
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    All-Graphene Planar Double-Quantum-Dot Resonant Tunneling Diodes
    Al-Dirini, F ; Mohammed, MA ; Hossain, FM ; Nirmalathas, TA ; Skafidas, E (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2016-01-01)
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    Highly Effective Conductance Modulation in Planar Silicene Field Effect Devices Due to Buckling
    Al-Dirini, F ; Hossain, FM ; Mohammed, MA ; Nirmalathas, A ; Skafidas, E (NATURE PUBLISHING GROUP, 2015-10-06)
    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. We illustrate this by using silicene to implement Self-Switching Diodes (SSDs), which are two-dimensional field effect nanorectifiers realized within a single silicene monolayer. Our quantum simulation results show that the atomically-thin silicene SSDs, with sub-10 nm dimensions, achieve a current rectification ratio that exceeds 200, without the need for doping, representing a 30 fold enhancement over graphene SSDs. We attribute this enhancement to a bandgap opening due to the in-plane electric field, as a consequence of silicene's buckling. Our results suggest that silicene is a promising material for the realization of planar field effect devices.
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    High Performance Graphene Nano-ribbon Thermoelectric Devices by Incorporation and Dimensional Tuning of Nanopores
    Hossain, MS ; Al-Dirini, F ; Hossain, FM ; Skafidas, E (NATURE PUBLISHING GROUP, 2015-06-17)
    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. We observe that the side channel width plays an important role to achieve optimal performance while the effect of pore length is less pronounced. This result is consistent with the fact that electronic conduction in GNRs is dominated along its edges. Ballistic transport regime is assumed and a semi-empirical method using Huckel basis set is used to obtain the electrical properties, while the phononic system is characterized by Tersoff empirical potential model. The proposed device structure has potential applications as a nanoscale local cooler and as a thermoelectric power generator.
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    Graphene Field Effect Nanopore Glycine Detector
    Al-Dirini, F ; Hossain, MS ; Qiu, W ; Hossain, FM ; Nirmalathas, A ; Skafidas, E (IEEE, 2014-01-01)