Gated Epitaxial Graphene Devices

2012 ◽  
Vol 717-720 ◽  
pp. 675-678
Author(s):  
Daniel Waldmann ◽  
Johannes Jobst ◽  
Florian Speck ◽  
Thomas Seyller ◽  
Michael Krieger ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Doping Concentration ◽  
Control Experiment ◽  
Uv Light ◽  
Epitaxial Graphene ◽  
Gate Operation ◽  
Uv Illumination ◽  
Gate Structure ◽  
Graphene Devices ◽  
Bottom Gate

A bottom gate scheme is presented to tune the charge density of epitaxial graphene via a gate voltage while leaving the surface open for further manipulation or investigation. Depending on the doping concentration of the buried gate layer, the temperature and illumination, the bottom gate structure can be operated in two regimes with distinct capacitances. A model is proposed, which quantitatively describes the gate operation. The model is verified by a control experiment with an illuminated gate structure using UV light. Using UV illumination the Schottky capacitor (SC) regime, which provides improved gate efficiency, can be used even at low temperatures.

scholarly journals ZnO Nanoparticles with Controllable Ce Content for Efficient Photocatalytic Degradation of MB Synthesized by the Polyol Method

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 71
Author(s):  
Gregorio Flores-Carrasco ◽  
Micaela Rodríguez-Peña ◽  
Ana Urbieta ◽  
Paloma Fernández ◽  
María Eugenia Rabanal
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Degradation ◽  
Doping Concentration ◽  
Polyol Method ◽  
Transmission Microscopy ◽  
Uv Illumination ◽  
Transmission Electron ◽  
Optical Luminescence ◽  
Pl Emission ◽  
Ce Content

This paper reports on the synthesis of Ce-doped ZnO (CZO) nanoparticles (NPs) by an alternative polyol method at low temperature. The method, facile and rapid, uses acetate-based precursors, ethylene glycol as solvent, and polyvinylpyrrolidone as capping agent. The effects of the Ce-doping concentration (ranging from 0 to 8.24 atomic%) on the structural, morphological, compositional, optical, luminescence, and photocatalytic properties of the NPs were investigated by several techniques. The structural findings confirmed that the CZO NPs have a typical hexagonal wurtzite-type structure with a preferred orientation along the (101) plane. The results obtained by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) revealed that the NPs size decreased (from ~30 to ~16 nm) with an increase in the Ce-doping concentration. Energy Dispersive X-Ray Spectroscopy (EDS) and High Resolution Transmission Microscopy (HRTEM) results confirmed the incorporation of Ce ions into the ZnO lattice. Ce-doping influences the photoluminescence (PL) emission compared to that of pure ZnO. The PL emission is related to the presence of different kinds of defects, which could take part in charge transfer and/or trapping mechanisms, hence playing an essential role in the photocatalytic activity (PCA). In fact, in this work we report an enhancement of PCA as a consequence of Ce-doping. In this sense, the best results were obtained for samples doped with 3.24 atomic%, that exhibited a photocatalytic degradation efficiency close to 99% after 60 min ultraviolet (UV) illumination, thus confirming the viability of Ce-doping for environmental applications.

Optical and Electrical Characterizations of Nanoscale Robust 3C-SiC Membrane for UV Sensing Applications

2018 ◽  
Vol 775 ◽  
pp. 278-282
Author(s):  
A.R.M. Foisal ◽  
T. Dinh ◽  
A. Iacopi ◽  
L. Hold ◽  
E.W. Streed ◽  
...  
Keyword(s):  
Uv Light ◽  
Optical Characterization ◽  
Considerable Change ◽  
Electrical Contacts ◽  
Si Substrate ◽  
Uv Illumination ◽  
Sensing Applications ◽  
Transmission Measurements ◽  
Electrical Characterizations

This paper presents the fabrication and optical characterization of an ultrathin 3C-SiC membrane for UV light detection. SiC nanoscale film was grown on Si substrate and subsequently released to form a robust membrane with a high aspect ratio of about 5000. Transmission measurements were performed to determine the thickness of the film with a high accuracy of 98%. We also employed a simple and highly effective direct wirebonding technique to form electrical contacts to the SiC membrane. The considerable change in the photocurrent of the SiC membrane was observed under UV illumination, indicating the potential of using 3C-SiC membranes for UV detection.

Graphene Nano-Biosensors for Detection of Cancer Risk

2012 ◽  
Vol 711 ◽  
pp. 246-252 ◽  
Author(s):  
Owen J. Guy ◽  
Gregory Burwell ◽  
Zari Tehrani ◽  
Ambroise Castaing ◽  
Kelly Ann Walker ◽  
...  
Keyword(s):  
High Vacuum ◽  
Epitaxial Graphene ◽  
Electrical Signal ◽  
Early Detection Of Disease ◽  
Disease Biomarkers ◽  
Sensing Applications ◽  
Highly Sensitive ◽  
Surface Functionalisation ◽  
Graphene Devices ◽  
Modified Graphene

Biosensor diagnostics based on bio-functionalized semiconductor devices are an important development in ultrasensitive sensors for early detection of disease biomarkers. Electrochemical devices using chemically modified graphene (CMG) channels are excellent candidates for nanobiosensors. This paper presents the development of novel antibody functionalized epitaxial graphene devices for bio-sensing applications. Epitaxial graphene has been grown on silicon carbide (SiC) substrates under high vacuum and high temperature conditions (1200 – 1700°C). A generic electrochemical surface functionalisation chemistry, which can be used to attach a variety of “bio-receptors” to graphitic surfaces, has been developed. The attached bio-receptors are capable of specific and selective interaction with disease biomarkers. When a target biomarker molecule interacts with the “bio-receptor” functionalized surface, the charge density at that surface is affected. This change can be detected as an electrical signal from the biosensor, enabling highly sensitive (nM) detection of biomarker analytes. This paper reports the fabrication of graphene channel sensors for detection of disease biomarkers.

Photochemisch initiierte Telomerisation von Äthylen mit Formamid / Photo-Initiated Telomerization of Ethylene with Formamide

1975 ◽  
Vol 30 (9-10) ◽  
pp. 740-747 ◽  
Author(s):  
H. P. Rath ◽  
A. Saus ◽  
B. Dederichs
Keyword(s):  
High Pressure ◽  
Reaction Time ◽  
Low Temperatures ◽  
Carbonic Acid ◽  
Uv Light ◽  
Electrical Power ◽  
Power Input ◽  
Elevated Pressure ◽  
Reaction Pressure ◽  
Geometrical Progression

Under the influence of UV light (high pressure HPK 125, Philips) and in presence of acetone ethylene and formamide react under elevated pressure (12.5-100 kp/cm2) to give odd-numbered n-alkane carbonic acid amides of chain lenghth C3-C19. Product yields improve with rising pressure. By increasing the concentration of aceton (0.1-8 mol-%), the reaction pressure the reaction time and at low temperatures the average mol.-weight is shifted to higher values. The chain distribution corresponds to a geometrical progression. Per 1 kwh electrical power input of the uv-equipment 0.5 kg of product is formed with chain length: 78% C3-C7, 12% C9, 10% C11-C19.

scholarly journals Nanorod Arrays Enhanced UV Light Response of Mg-Doped ZnO Films

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1005
Author(s):  
Der-Yuh Lin ◽  
Hone-Zern Chen ◽  
Ming-Cheng Kao ◽  
San-Lin Young ◽  
Wen-Yi Sung
Keyword(s):  
Uv Light ◽  
Sol Gel ◽  
Light Response ◽  
Band Gap Energy ◽  
Zno Films ◽  
Silicon Substrates ◽  
Nanorod Arrays ◽  
Nanocrystalline Films ◽  
Uv Illumination ◽  
Surface Morphologies

Zn1−xMgxO (x = 0, 0.03, 0.05, and 0.07) nanocrystalline films were grown on silicon substrates using the sol–gel method. Furthermore, Zn1−xMgxO vertically aligned hexagonal symmetrical nanorods with six reflection symmetries were fabricated on pure ZnO-seeded layer n-type silicon substrates via a low-temperature hydrothermal method to enhance the ultraviolet (UV) light response. The crystal microstructures and surface morphologies of nanocrystalline films and nanorod arrays were determined by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Transmission spectra showed that the increasing Mg content will increase the band gap energy from 3.28 to 3.46 eV. However, the current–voltage curves in the dark and under UV illumination showed that the UV response did not improve by the incorporation of magnesium. We changed the flat surface of films into symmetrical nanorod arrays and demonstrated they can significantly enhance the normalized photo-to-dark-current ratio up to ten times.

Pentacene Organic Thin-Film Transistors with Dual-Gate Structure

2007 ◽  
Vol 124-126 ◽  
pp. 383-386
Author(s):  
Jae Bon Koo ◽  
Jung Wook Lim ◽  
Chan Hoe Ku ◽  
Sang Chul Lim ◽  
Jung Hun Lee ◽  
...  
Keyword(s):  
Thin Film ◽  
Electrostatic Potential ◽  
Thin Film Transistors ◽  
Gate Dielectric ◽  
Atomic Layer ◽  
Organic Thin Film Transistors ◽  
Organic Thin Film ◽  
Gate Structure ◽  
Dual Gate ◽  
Bottom Gate

We report on the fabrication of dual-gate pentacene organic thin-film transistors (OTFTs) using a plasma-enhanced atomic layer deposited (PEALD) 150 nm thick Al2O3 as a bottom gate dielectric and a 300 nm thick parylene or a PEALD 200 nm thick Al2O3 as both a top gate dielectric and a passivation layer. The threshold voltage (Vth) of OTFT with a 300 nm thick parylene as a top gate dielectric is changed from 4.7 V to 1.3 V and that with a PEALD 200 nm thick Al2O3 as a top gate dielectric is changed from 1.95 V to -9.8 V when the voltage bias of top gate electrode is changed from -10 V to 10 V. The change of Vth of OTFT with the dual-gate structure has been successfully understood by an analysis of electrostatic potential.

scholarly journals High mobility epitaxial graphene devices via aqueous-ozone processing

2015 ◽  
Vol 106 (6) ◽  
pp. 063503 ◽  
Author(s):  
Tom Yager ◽  
Matthew J. Webb ◽  
Helena Grennberg ◽  
Rositsa Yakimova ◽  
Samuel Lara-Avila ◽  
...  
Keyword(s):  
High Mobility ◽  
Epitaxial Graphene ◽  
Graphene Devices

scholarly journals Low Carrier Density Epitaxial Graphene Devices On SiC

Small ◽  
2014 ◽  
Vol 11 (1) ◽  
pp. 90-95 ◽  
Author(s):  
Yanfei Yang ◽  
Lung-I. Huang ◽  
Yasuhiro Fukuyama ◽  
Fan-Hung Liu ◽  
Mariano A. Real ◽  
...  
Keyword(s):  
Carrier Density ◽  
Epitaxial Graphene ◽  
Graphene Devices
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