Reduced Graphene Oxide Based Schottky Diode on Flex Substrate for Microwave Circuit Applications (original) (raw)

CNT and Graphene based Diodes for Microwave and Millimeter wave Circuits on Flexible Substrates

This paper presents the fabrication and characterization of carbon nanomaterials, i.e., carbon nanotubes (CNTs) and reduced graphene oxide (r-GO), based diodes on flexible substrates for high-frequency circuit applications. CNTs and graphene are good candidates as they possess excellent electronic and mechanical properties. For high-frequency circuits, diodes with lower parasitics and optimal impedance are required to achieve a high cutoff frequency and ease of impedance matching. Here, multiple CNTs are arranged in parallel to reduce the series resistance and to lower the impedance value, whereas 2-D graphene readily provides the desired impedance values. CNT and r-GO diodes with dissimilar metal contacts are fabricated using a novel process on high-frequency-compatible flexible substrates. The process utilizes an undercut and self-alignment approach that allows fabrication of submicrometer-size devices using an all-photolithographic process. The fabricated diodes demonstrate nonlinear current-voltage characteristics with current in the microampere range. Both types of diodes work efficiently as microwave rectifiers showing a near-ideal behavior with a rectification sensitivity of 4 V/W (18 GHz) and 33 V/W (22 GHz) for the CNT and r-GO, respectively. In addition, the results for r-GO-based frequency multiplication at fundamental frequencies ranging from 2 to 6 GHz and frequency mixing for 1.5 and 1.0 GHz are also presented.

Schottky Diode Graphene Based Sensors

International Journal on Smart Sensing and Intelligent Systems, 2020

In this paper, we aim to demonstrate a novel scheme for integration of nanostructured semiconductor Graphene Oxide (GO) shottky diodes on flexible substrate for a wide range of sensing applications. The platform introduces a novel flexible GO/Pt/n-Si and GO/Pt/SiN composite structures which provides excellent optical and electrical properties, while maintaining an acceptable mechanical, biocompatibility, and return loss performance. The new structure was investigated for glucose, radiation, and infrared sensing. The sensors results showed ultrahigh sensitivity and high linearity in the targeted regions of interest. Moreover, the use of nanostructured materials allows for the development of a new generation of modern printed circuit antennas and will enable wide range of applications merging both technologies for a wide range of wearable and implantable sensing devices.

Back-to-Back Schottky Diode from Vacuum Filtered and Chemically Reduced Graphene Oxide

Indonesian Journal of Electrical Engineering and Computer Science, 2018

This paper presents fabrication of reduced graphene oxide (rGO)/silicon (Si) back-to-back Schottky diode (BBSD) through graphene oxide (GO) thin film formation by vacuum filtration and chemical reduction of the film via ascorbic acid. In order to understand and assess the viability of these two processes, process condition and parameters were varied and analyzed. It was confirmed that the GO film thickness could be controlled by changing GO dispersion volume and concentration. Filtration of 200 ml of 0.4 ppm GO dispersion produced average film thickness of 53 nm. As for the reduction process, long duration was required to produce higher reduction degree. rGO film that underwent two times reduction at before and after transfer process with concentrated ascorbic acid gave the lowest sheet resistance of 3.58 MΩ/sq. In the final part of the paper, result of the BBSD device fabrication and current-voltage characterization were shown. The formed two rGO/Si Schottky junctions in the BBSD gave barrier height of 0.63 and 0.7 eV. The presented results confirmed the viability of fabricating rGO-based device using a simple method and without requirement of sophisticated equipment.

Graphene FETs in Microwave Applications

COVER: From left to right, a SEM image of graphene nanoconstrictions, a SEM image of a two-finger gate graphene FET, drain current versus intrinsic V gs and V gd , I-V output characteristic and an integrated subharmonnic G-FET mixer.

State-of-the-Art Graphene High-Frequency Electronics

Nano Letters, 2012

High-performance graphene transistors for radio frequency applications have received much attention and significant progress has been achieved. However, devices based on large-area synthetic graphene, which have direct technological relevance, are still typically outperformed by those based on mechanically exfoliated graphene. Here, we report devices with intrinsic cutoff frequency above 300 GHz, based on both wafer-scale CVD grown graphene and epitaxial graphene on SiC, thus surpassing previous records on any graphene material. We also demonstrate devices with optimized architecture exhibiting voltage and power gains reaching 20 dB and a wafer-scale integrated graphene amplifier circuit with voltage amplification.

RF DEVICE CHARACTERIZATION OF GRAPHENE TRANSISTORS

ProQuest, 2023

Radio Frequency performance of field-effect transistors has been explored in depth, experimented and industrially in use since a long time. Whenever one thinks of transistors which could take us to the regime of more than 1 THz in frequency it would always be the High Electron Mobility Transistors (HEMTS) as the perfect solution to that. The Graphene transistors have been very much in research from 2010 and promise equal results due to their huge potential in mobility. In the Semiconductor Manufacturing And Fabrication Laboratory at the Rochester Institute Of Technology our research group has been designing, fabricating and characterizing the graphene transistors of top-gated and back- gated varieties of which the former has been more explored and characterized because of its potential in high frequency performance. In this thesis characterization of both the top-gated and the back-gated varieties will be discussed in intricate detail with different permutation and combinations in experiments in order to depict the efficiency of these transistors in terms of their frequency characteristics and the possible ways to optimize the mobility and transconductance, thereby changing the hysteresis behaviours of the top-gated transistors. The maximum oscillation frequency has been explored for the top- gated variant where it can be estimated how they are in performance and exhibit unique nature compared to that of the PMOS and the NMOS devices along with this distinctive hysteresis behaviours by application of a polymer on GFETs has been investigated.

Microwave Power Detection With Voltage-Gated Graphene

IEEE Open Journal of Nanotechnology

Commercially available, chemical vapor deposition grown, graphene has been used to realize voltage-gate tunable, microwave power detectors. Corbino disc structures with chrome/gold contacts have been fabricated on top of graphene deposited on P-type silicon substrates with silicon dioxide gate oxides. Devices of varying sizes were used to detect a 433.92 MHz signal. These test structures exhibited a peak power detection sensitivity of 3.25 mV/mW at 292 K and 5.43 mV/mW at 80 K. The improved graphene detectors exceed the sensitivity of previously reported graphene detectors, 0.86 mV/mW, as well as previously explored carbon nanotube bolometers, 0.36 mV/mW.

Graphene integrated circuits: new prospects towards receiver realisation

Nanoscale, 2017

This work demonstrates a design approach which enables the fabrication of fully integrated radio frequency (RF) and millimetre-wave frequency direct-conversion graphene receivers by adapting the frontend architecture to exploit the state-of-the-art performance of the recently reported wafer-scale CVD metal-insulator-graphene (MIG) diodes. As a proof-of-concept, we built a fully integrated microwave receiver in the frequency range 2.1-2.7 GHz employing the strong nonlinearity and the high responsivity of MIG diodes to successfully receive and demodulate complex, digitally modulated communication signals at 2.45 GHz. In addition, the fabricated receiver uses zero-biased MIG diodes and consumes zero dc power. With the flexibility to be fabricated on different substrates, the prototype receiver frontend is fabricated on a low-cost, glass substrate utilising a custom-developed MMIC process backend which enables the high performance of passive components. The measured performance of the p...

Applications of Graphene at Microwave Frequencies

Radioengineering, 2015

In view to the epochal scenarios that nanotechnology discloses, nano-electronics has the potential to introduce a paradigm shift in electronic systems design similar to that of the transition from vacuum tubes to semiconductor devices. Since low dimensional (1D and 2D) nano-structured materials exhibit unprecedented electromechanical properties in a wide frequency range, including radio-frequencies (RF), microwave nano-electronics provides an enormous and yet widely undiscovered opportunity for the engineering community. Carbon nanoelectronics is one of the main research routes of RF/microwave nano-electronics. In particular, graphene has shown proven results as an emblematic protagonist, and a real solution for a wide variety of microwave electronic devices and circuits. This paper introduces graphene properties in the microwave range, and presents a paradigm of novel graphene-based devices and applications in the microwave/RF frequency range.