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 Investigating cell membranes: researchers develop a substance mimicking a vital membrane component
25.05.2018 | Westfälische Wilhelms-Universität Münster

nachricht New approach: Researchers succeed in directly labelling and detecting an important RNA modification
30.04.2018 | Westfälische Wilhelms-Universität Münster

All articles from Interdisciplinary Research >>>

The most recent press releases about innovation >>>

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

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

Im Focus: Water is not the same as water

Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.

From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

A sprinkle of platinum nanoparticles onto graphene makes brain probes more sensitive

15.06.2018 | Materials Sciences

100 % Organic Farming in Bhutan – a Realistic Target?

15.06.2018 | Ecology, The Environment and Conservation

Perovskite-silicon solar cell research collaboration hits 25.2% efficiency

15.06.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>