We propose and extensively analyze a novel Graphene-FET (GFET) with two capacitively coupled field-controlling electrodes (FCE) at the ungated access regions between gate and source/drain. The FCEs are proposed to be positioned both on top and bottom of the device. The FCEs could be independently biased to modulate sheet carrier concentration and thereby the resistance in the ungated regions. The reduction of source/drain access resistance results in increased cut off frequency compared to those of conventional GFETs with the same geometry. The DC and improved RF characteristics of the proposed device have been studied using both analytical and numerical techniques and compared with the baseline designs.
We report on sub-wavelength THz plasmonic lenses based on 2 dimensional electron gas (2DEG) at AlGaN/GaN
interface and also on few-layer graphene sheets. Circular gratings investigated in this study concentrate THz electric
field into deep sub-wavelength scale by plasmonic excitations polarization independently. Propagation of a broadband
pulse of EM waves in 0.5-10 THz was simulated by using a commercial FDTD simulation tool. The results show that
concentric plasmonic grating structures can be used to concentrate THz into deep sub-wavelength down to λ/350 spot
size and achieve very large field enhancements by plasmonic confinement which can be used for THz detection and
possibly for sub-wavelength imaging. Electric field intensity under the central point can be orders of magnitude higher
than the outer grating area. Moreover, plasmonic lens modes supported by system can be tuned with an applied voltage
This paper presents our recent results on carbon nanomaterials for applications in energy storage and bio-sensor. More
specifically: (i) A novel binder-free carbon nanotubes (CNTs) structure as anode in Li-ion batteries. The interfacecontrolled
CNT structure, synthesized through a two-step chemical vapor deposition (CVD) and directly grown on
copper current collector, showed very high specific capacity - almost three times as that of graphite, excellent rate
capability. (ii) A large scale graphene film was grown on Cu foil by thermal chemical vapor deposition and transferred to
various substrates including PET, glass and silicon by using hot press lamination and etching process. The graphene/PET
film shows high quality, flexible transparent conductive structure with unique electrical-mechanical properties; ~88.80 %
light transmittance and ~ 100 Ω/sq sheet resistance. We demonstrate application of graphene/PET film as flexible and
transparent electrode for field emission displays. (iii) Application of individual carbon nanotube as nanoelectrode for
high sensitivity electrochemical sensor and device miniaturization. An individual CNT is split into a pair of
nanoelectrodes with a gap between them. Single molecular-level detection of DNA hybridization was studied.
Hybridization of the probe with its complementary strand results in an appreciable change in the electrical output signal.