Laser direct patterning of graphene on hard substrates for nano-electronic fabrication
Graphene is being considered as an ideal material for all-carbon-based micro/nanoscale electronics owing to its extraordinary electronic property, chemical stability, and unique two-dimensional nanostructure. Nowadays, many methods, including thermal graphitization or chemical vapor deposition with a pre-patterned catalyst on substrates and a micro-contact printing technique, have been explored to fabricate graphene based nano-electronics. However, all of these approaches require conventional lithographic techniques, high temperature, or a predefined patterned mask, which have the shortcomings of high production cost, low manufacturing yield, high time consumption, environmental pollution, and/or precluding the use of hard plastics as substrates for device fabrication.? For overcoming the technical challenges, we thus propose the use of laser micro-machining of graphene to pattern graphene on hard substrates, characterize the interaction between laser and graphene, evaluate the potential of this novel application and do optimization. The proposed laser processing technology for patterning graphene will promisingly bring a high volume fabrication of advanced electronics.
R&D Methodology
The laser processing parameters and material selection for laser direct patterning of graphene will be investigated. This relates the laser parameters (output power, wavelength, and polarization), structure modification and phase change of graphene. The interaction between graphene and graphene derivatives and laser will be studied. Graphene, graphene oxide, bulk graphite will be selected to irradiate with different lasers available on campus such as YAG laser and excimer laser. Topography of the irradiated areas will be analysed to compare with as-received areas. Depth profiles will also be studied. Potential phase changes and structure modifications will be identified. Among the initial findings, findings that have potential to applications will be studied thoroughly by modifying conditions of the interaction between laser and samples.
These conditions include:
- On the aspect of laser: continuous/ pulse mode, peak energy/ averaged power, pulse duration, repetition rate, repetition, spot size, spot shape, scan speed, bite length and so on are factors to optimize. It is necessary to identify significant factors that affect the interaction effectively.
- On the aspect of material: graphene and graphene oxide could be prepared in different percentage ratios, thickness and fabrication processes.
The experimental results will be analyzed for its mechanism by physical modeling of the laser activation process. The modeling will be based on existing models. New key factors that characterize ultra-thin (one/few atomic layers) film will be included in the model.
Objectives and Benefits
(1) A mechanism study of the interaction between laser and one-layer/few-layer graphene by different laser systems such as excimer laser and YAG laser,
(2) An identification of different interacting regimes in terms of photo-induced structure-modification of graphene. The structural modification will then be related to the conductivity of the reduced graphene.
(3) A methodology of laser micro-machining technology for patterning graphene and forming conductive circuits at the same time on hard substrates (e.g. glass and silicon). The relative increase in conductivity is expected to be as high as four orders of magnitude with 90% yield.
Deliverables:
- A detailed interaction mechanism between laser and one-layer/few-layer graphene will be identified,
- A methodology of laser micro-machining technology for patterning graphene on hard substrates (e.g. glass and silicon) by different laser systems such as excimer laser and YAG laser will be developed, and
- 3.5″ touch screen panel prototype by using this project know-how with the following specification will be demonstrated:
- Thickness of the film: less than 10 nm,
- Optical transmission: more than 90 %, and
- sheet resistance: less than 150 ohm/sq
Project Commencement Date:
01 June, 2012
Project Completion Date:
31 May , 2014
Principal Investigator:
Dr. Winco K.C. Yung
Tel (852) 2766-6599
Project Team Members:
1.Dr Winco K.C. Yung
2.Prof T.M. Yue
3.Dr H.M. Liem
4.Dr H.S.Choy
5.Ms Joanne Wong
