Thickness control of graphene deposited over polycrystalline nickel

2015 ◽  
Vol 39 (6) ◽  
pp. 4414-4423 ◽  
Author(s):  
Ma Prado Lavin-Lopez ◽  
Jose Luis Valverde ◽  
Ma Inmaculada Ruiz-Enrique ◽  
Luz Sanchez-Silva ◽  
Amaya Romero
Keyword(s):  
Monolayer Graphene ◽  
Polycrystalline Nickel ◽  
Inexpensive Method ◽  
Thickness Control ◽  
Cvd Graphene

77% of a polycrystalline nickel sheet has been covered with monolayer graphene, demonstrating an inexpensive method to synthesize CVD-graphene.

scholarly journals Influence of the Total Gas Flow at Different Reaction Times for CVD-Graphene Synthesis on Polycrystalline Nickel

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
M. P. Lavin-Lopez ◽  
J. L. Valverde ◽  
L. Sanchez-Silva ◽  
A. Romero
Keyword(s):  
Reaction Time ◽  
Gas Flow ◽  
Reaction Times ◽  
Monolayer Graphene ◽  
Graphene Monolayer ◽  
Multilayer Graphene ◽  
Reaction Step ◽  
Polycrystalline Nickel ◽  
Cvd Graphene ◽  
Graphene Synthesis

Optimization of the total gas flow (CH4+H2) during the reaction step for different reaction times for CVD-graphene synthesis on polycrystalline nickel foil using an atmospheric pressure set-up is reported. Athickness valuerelated to number of graphene layers in each of the synthesized samples was determined using an Excel-VBA application. This method assigned athickness valuebetween 1 and 1000 and provided information on the percentage of each type of graphene (monolayer, bilayer, and multilayer) deposited onto the polycrystalline nickel sheet. The influence of the total gas flow during the reaction step and the reaction time was studied in detail. Optical microscopy showed that samples were covered with different types of graphene, such as multilayer, few-layer, bilayer, and monolayer graphene. The synthesis variables were optimized according to thethickness valueand the results were verified by Raman spectroscopy. The best conditions were obtained with a reaction temperature of 980°C, a CH4/H2flow rate ratio of 0.07 v/v, a reaction time of 1 minute, and a total gas flow of 80 NmL/min. In the sample obtained under the optimized conditions, 80% of the area was covered with monolayer graphene and less than 1% with multilayer graphene.

scholarly journals Quantum Hall Effect across Graphene Grain Boundary

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 8
Author(s):  
Tuan Khanh Chau ◽  
Dongseok Suh ◽  
Haeyong Kang
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Quantum Hall ◽  
Chemical Vapor ◽  
Hall Resistance ◽  
Monolayer Graphene ◽  
Cvd Graphene ◽  
Carrier Scattering ◽  
Longitudinal Resistance ◽  
Charge Carrier Scattering

Charge carrier scattering at grain boundaries (GBs) in a chemical vapor deposition (CVD) graphene reduces the carrier mobility and degrades the performance of the graphene device, which is expected to affect the quantum Hall effect (QHE). This study investigated the influence of individual GBs on the QH state at different stitching angles of the GB in a monolayer CVD graphene. The measured voltage probes of the equipotential line in the QH state showed that the longitudinal resistance (Rxx) was affected by the scattering of the GB only in the low carrier concentration region, and the standard QHE of a monolayer graphene was observed regardless of the stitching angle of the GB. In addition, a controlled device with an added metal bar placed in the middle of the Hall bar configuration was introduced. Despite the fact that the equipotential lines in the controlled device were broken by the additional metal bar, only the Rxx was affected by nonzero resistance, whereas the Hall resistance (Rxy) revealed the well-quantized plateaus in the QH state. Thus, our study clarifies the effect of individual GBs on the QH states of graphenes.

HIGH FREQUENCY GRAPHENE TRANSISTORS USING LARGE-AREA CVD GRAPHENE AND ADVANCED DIELECTRICS

2011 ◽  
Vol 20 (03) ◽  
pp. 669-677
Author(s):  
OSAMA M. NAYFEH ◽  
TONY IVANOV ◽  
JAMES WILSON ◽  
ROBERT PROIE ◽  
MADAN DUBEY
Keyword(s):  
High Frequency ◽  
Gate Dielectric ◽  
Chemical Vapor ◽  
Hole Mobility ◽  
Monolayer Graphene ◽  
Large Area ◽  
Cvd Graphene ◽  
Ambipolar Behavior ◽  
Chemical Vapor Deposited ◽  
First Time

Graphene transistors using large area chemical-vapor-deposited (CVD) monolayer graphene and advanced dielectric stacks are constructed and examined. Top-gated devices with a SiO 2/ Al 2 O 3 gate-dielectric have a Dirac Point (DP) located at less than 5 V and asymmetric electron/hole mobility. In contrast, devices based on an advanced AlN interfacial layer have a DP located near 0V and a near symmetric carrier mobility- characteristics that could be more suitable for applications that require ambipolar behavior and low-power operation. For the first time, a measured RF cut-off frequency range of 1GHz is measured for top-gated transistors using CVD graphene. The results are of importance for the realization of graphene based, wafer-scale, high frequency electronics.

HIGH FREQUENCY TOP-GATED GRAPHENE RF AMBIPOLAR FETs USING LARGE-AREA CVD GRAPHENE AND ADVANCED DIELECTRICS

2011 ◽  
Vol 1283 ◽  
Author(s):  
Osama M. Nayfeh ◽  
Madan Dubey
Keyword(s):  
Dirac Point ◽  
Gate Dielectric ◽  
Field Effect Transistors ◽  
Hole Mobility ◽  
Monolayer Graphene ◽  
Large Area ◽  
Electron Hole ◽  
Cvd Graphene ◽  
Graphene Fet ◽  
P Type

ABSTRACTAmbipolar top-gated field effect transistors (FETs) based on large area Cu catalyzed CVD-grown monolayer graphene interfaced to advanced dielectrics have been constructed and examined both for their material and electrical qualities. Interfacing of the graphene with novel insulators/substrates could be tailored for the particular application and provide for enhanced device functionality. In contrast to graphene FETs using SiO2-based top-gate dielectric, which show asymmetric electron/hole mobility (with larger hole mobility), and Dirac point shifted to positive levels, FETs constructed using advanced AlN show Dirac point almost near neutral levels and near symmetric electron/hole mobility. The DP is shifted likely due to compensation of the intrinsic p-type doping by n-type doping introduced by the AlN deposition and potentially via a contribution of polarization-induced carrier density. Finally, we demonstrate a top-gated graphene FET with the first observation of RF operation with GHz cut-off frequency based on large area CVD graphene.

scholarly journals Highly uniform monolayer graphene synthesis via a facile pretreatment of copper catalyst substrates using an ammonium persulfate solution

RSC Advances ◽  
2019 ◽  
Vol 9 (36) ◽  
pp. 20871-20878 ◽  
Author(s):  
Hyunhak Jeong ◽  
Wang-Taek Hwang ◽  
Younggul Song ◽  
Jae-Keun Kim ◽  
Youngrok Kim ◽  
...  
Keyword(s):  
Copper Catalyst ◽  
Ammonium Persulfate ◽  
Monolayer Graphene ◽  
Large Area ◽  
Graphene Growth ◽  
Cvd Graphene ◽  
Graphene Synthesis ◽  
Highly Uniform

A facile method for preparing a pretreated copper catalyst substrate for highly uniform, large-area CVD graphene growth is proposed.

Improving the growth of monolayer CVD-graphene over polycrystalline iron sheets

2017 ◽  
Vol 41 (12) ◽  
pp. 5066-5074 ◽  
Author(s):  
M. P. Lavin-Lopez ◽  
M. Fernandez-Diaz ◽  
L. Sanchez-Silva ◽  
J. L. Valverde ◽  
A. Romero
Keyword(s):  
Graphene Film ◽  
Monolayer Graphene ◽  
Iron Foil ◽  
High Quality ◽  
Polycrystalline Iron ◽  
Cvd Graphene

A high quality graphene film, mostly composed of monolayer graphene, was successfully grown on polycrystalline iron foil by atmospheric CVD process using methane as carbonaceous source.

Role of inert gas in the Cvd-graphene synthesis over polycrystalline nickel foils

2019 ◽  
Vol 222 ◽  
pp. 173-180 ◽  
Author(s):  
M.P. Lavin-Lopez ◽  
J.L. Valverde ◽  
S. Ordoñez-Lozoya ◽  
A. Paton-Carrero ◽  
A. Romero
Keyword(s):  
Inert Gas ◽  
Polycrystalline Nickel ◽  
Cvd Graphene ◽  
Graphene Synthesis

Voids in Quenched Nickel

1968 ◽  
Vol 26 ◽  
pp. 266-267
Author(s):  
J. J. Laidler
Keyword(s):  
Electron Beam ◽  
Ambient Temperature ◽  
Cooling Rate ◽  
Three Dimensional ◽  
Cooling Curve ◽  
Polycrystalline Nickel ◽  
Quenching Temperature ◽  
Long Tail ◽  
Diffusion Pump

The presence of three-dimensional voids in quenched metals has long been suspected, and voids have indeed been observed directly in a number of metals. These include aluminum, platinum, and copper, silver and gold. Attempts at the production of observable quenched-in defects in nickel have been generally unsuccessful, so the present work was initiated in order to establish the conditions under which such defects may be formed.Electron beam zone-melted polycrystalline nickel foils, 99.997% pure, were quenched from 1420°C in an evacuated chamber into a bath containing a silicone diffusion pump fluid . The pressure in the chamber at the quenching temperature was less than 10-5 Torr . With an oil quench such as this, the cooling rate is approximately 5,000°C/second above 400°C; below 400°C, the cooling curve has a long tail. Therefore, the quenched specimens are aged in place for several seconds at a temperature which continuously approaches the ambient temperature of the system.

Size effect in conductivity of polycrystalline nickel films

2010 ◽  
Vol 28 (0) ◽  
pp. 37-43
Author(s):  
А. Г. Басов ◽  
Ю. О. Шкурдода ◽  
Л. В. Дехтярук
Keyword(s):  
Size Effect ◽  
Polycrystalline Nickel ◽  
Nickel Films

Simultaneous Diameter and Thickness Control in Tube Extrusion

1991 ◽  
Vol 6 (3) ◽  
pp. 188-194 ◽  
Author(s):  
G. Defaye ◽  
L. Caralp ◽  
B. Delfanne ◽  
J. J. Labaig
Keyword(s):  
Thickness Control ◽  
Tube Extrusion
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