Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Graphene: Patterning and doping

14.07.2011
Innovative approaches for patterning graphene oxide and chemical doping of graphene for nanoelectronics.

The chemical synthesis of graphene is considered as an efficient means of mass producing graphene-based compounds. Typically, the chemical process of producing graphene consists of first chemical exfoliation of graphite to produce graphene oxide (GO) flakes, followed by the reduction of the GO, which yields graphene flakes.

Now in spite of the proliferation of chemical approaches for the synthesis there are still two fundamental issues to resolve. First is the development of protocols for integrating chemical synthesis with device fabrication technology, namely, methods for the positioning GO or graphene flakes at specific locations on substrates to enable photolithography and device fabrication, without having to ‘hunt’ for graphene. The second issue is an effective and controlled means of doping graphene in solution—again an important factor for real life applications of this material.

Here in two recent publications, Adarsh Sandhu at Toyohashi University of Technology and colleagues demonstrate novel approaches to resolve the issues of device patterning and doping of graphene.

In JJAP [1] Adarsh Sandhu and his doctoral student Ryousuke Ishikawa describe a straightforward process for positioning individual flakes of graphene oxide at specific locations of a substrate and subsequent fabrication of device structures using individual flakes of chemically derived graphene. Notably, the researchers exploited the negatively charged surface of GO flakes, and successfully patterned GO flakes onto photolithographically defined positively charged regions on silicon substrates. The immobilized GO flakes were reduced in a saturated vapor of hydrazine monohydrate at 80°C for 18 h and post-annealing in vacuum. Electrical measurements using photolithographically defined Hall crosses showed the monolayer films of reduced GO films to have a carrier concentration and mobility of 1011 cm-2 and 10 cm2/Vs, respectively.

In addition, the researchers addressed the issue of doping in Nanoscale Research Letters [2], where they describe an inexpensive method of producing chemically derived graphene-based transparent conducting films (TCFs) via charge transfer by conjugated organic molecules. In this approach, the process of GO reduction and carrier doping were carried out in liquid phase, that is, without the use of vacuums, which is an advantage for mass production of doped graphene of touch panel displays and solar cell panels.

GO films produced by Hummer's method were reduced to form graphene by dispersing GO into an aqueous solution containing N2H4, a strong reductant (with NH3 to adjust pH) in a water bath at 95°C water bath for 1 h, when the and the color of the dispersion changed from brownish color to gray. Finally, the solvent of reduced graphene oxide (RGO) dispersion was replaced by N,N-dimethylformamide (DMF) using an evaporator.

Doping graphene via charge transfer by tetracyanoquinodimethane (TCNQ)—well-known as a powerful electron accepter, which is expected to favor electron transfer from graphene into TCNQ molecules, thereby leading to p-type doping of graphene films—molecules. Importantly, small quantities of TCNQ drastically improved the resistivity without degradation of optical transparency.

Reference
[1] Ryousuke Ishikawa1, Masashi Bando1, Yoshitaka Morimoto1, and Adarsh Sandhu1,2 Patterning of Two-Dimensional Graphene Oxide on Silicon Substrates Japanese Journal of Applied Physics 49, 06GC02, (2010)
Abstract: http://jjap.jsap.jp/link?JJAP/49/06GC02[2] Ryousuke Ishikawa1,2, Masashi Bando1, Yoshitaka Morimoto1, Adarsh Sandhu1,2 Doping graphene films via chemically mediated charge transfer Nanoscale Research Letters 6, 111, (2011)
Open access: http://www.nanoscalereslett.com/content/6/1/111Related information
1Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8552, Japan 2Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan

EIIRIS URL: http://www.eiiris.tut.ac.jp/

Adarsh Sandhu | Toyohashi University
Further information:
http://www.tut.ac.jp/english/newsletter/research_highlights/research04.html

More articles from Interdisciplinary Research:

nachricht New dental implant with built-in reservoir reduces risk of infections
18.01.2017 | KU Leuven

nachricht Many muons: Imaging the underground with help from the cosmos
19.12.2016 | DOE/Pacific Northwest National Laboratory

All articles from Interdisciplinary Research >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Tracking movement of immune cells identifies key first steps in inflammatory arthritis

23.01.2017 | Health and Medicine

Electrocatalysis can advance green transition

23.01.2017 | Physics and Astronomy

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>