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HELLO! I'M CHUN-DA.

Chun-Da Liao belongs to Nanodevices group in the department of Nanoelectronics Engineering at INL. He works on graphene massive production and the synthesis of large graphene single crystal through chemical vapor deposition, as well as the advanced graphene application and integration with other 2D materials.

 

 
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About CHUN-DA

Dr. Chun-Da Liao, winning his EPSRC Research Scholar from Engineering and Physical Sciences Research Council (United Kingdom) in 2014,  was a Research Scientist in both Material Science Center and National Graphene Institute at the University of Manchester in the United Kingdom, cooperating with Renold (Germany based company) and also carrying out several industrial projects  on the massive production of graphene using chemical vapor deposition, followed by joining BGT Materials (Industrial Partner of National Graphene Institute) as a senior Research Scientist/Project Leader.

He received the Ph. D. degree in optoelectronic engineering from National Taiwan University in 2010. During his doctoral study, he won the first place honor in NTU Ph. D. Qualify Examination and published five peer-reviewed research papers regarding the design of microcantilever sensors and MEMS scanning micromirrors. From September 2010 to December 2013, he received NTU Excellent Postdoctoral Fellowship (2010 - 2013, Taiwan), working at Institute of Atomic and Molecular Science, Academic Sinica based in National Taiwan University. During this period of time, he published five high-impact research papers and one book chapter on the research of graphene synthesis and their applications with 2D materials.

 

 

The Cofund project

Advanced Power Generator Using Graphene Microspiral Coils

The basic concept of this research project originates from conventional electromagnetic power generators converting mechanical energy to electrical energy, which have been extensively utilized in a variety of power plants. The core technique is the design of ultra-thin flexible polyimide/graphene micro-spiral coils, which is utilized for miniature and high-throughput power generators. The configuration of transparent polyimide/graphene micro-spiral coils is also able to be applied in ultra-thin wireless charging devices, solar/wind hybrid power system and wireless communication system.

The graphene-based micro-spiral coil is flexible, lightweight and ultra-sensitive to the change of the magnetic field. Through integration of tiny multipole magnets, this project aims to charge/power portable electronic devices through daily human movement such as vibration, walk and run.

 

Recent research

The Growth of Millimeter-Scaled Graphene Single Crystal through Nucleation Density Control in Height-Confined Reaction Cavity

(Oral presentation in 14th International Conference on Advance Nanomaterials, Aveiro, Portugal)

In conventional CVD process, the as-grown continuous graphene film over entire Cu foil could be regarded as the coalescence via many small graphene grains with lateral size of less than 50-60 µm in Figure (a). The dense graphene boundaries on continuous graphene films would introduce severe carrier scattering which degrades carrier mobility of graphene films, therefore retarding graphene related applications. In this work, the growth of high-quality large graphene grains through the nucleation density control in confined reaction cavity will effectively reduce the effective perimeter of graphene grain boundaries in graphene films and enhance its physical properties.

 Figure 1. Optical images of graphene single crystals

Figure 1. Optical images of graphene single crystals

The height-confined slit positioned in an enclosed graphite cavity is designed for graphene growth. The Cu sublimation is suppressed within the confined slit, therefore reducing the surface roughness of Cu substrate and graphene nucleation density. The less dendrite-edged graphene single crystals were successfully grown in graphite cavity and height-confined graphite slit as shown in Figure (c) and (d). Besides the control of the growth environment, the oxidized Cu foils are utilized for the fast growth due to the low reaction rate within the confined slit. The surface oxygen not only passivate the Cu active sites to diminish the graphene nucleation density, but also lower the surface reaction barrier to accelerate the growth rate. (d) shows the size of graphene grains is up to millimeter scaled before coalescence.

Low-Residue Transfer of CVD Graphene Using Supporting Layer of Low Average Molecular Weight PMMA-mixture

 Figure 1. MicroRaman mapping of graphene single crystal

Figure 1. MicroRaman mapping of graphene single crystal

In this study, the optimized PMMA-mixture was successfully utilized in low-residue transfer of the as-gown graphene. The supporting layer of PMMA-mixture can endure at least 5-6 complete cycles of transfer in the rinse process, which demonstrates its sufficient tensile strength can protect graphene from damage during entire process of wet transfer. PMMA-15k leads the role of de-polymerization promoter, which decrease the degree of being tangled between long chain molecules of PMMA-550k.  The results of Raman analysis revealed CVD-grown graphene transferred by the supporting layer of PMMA-mixture received the less p-type doping, i.e., the achievement of residue elimination. Up to 7 cm-1 blue-shift of G band frequency can be observed in graphene sample transferred by the supporting layer of PMMA-950k.  The raised p-type doping would block the decay pathway of electron–hole pairs leading to the narrower band width of G peak. The experimental results of Raman analysis demonstrated the highest doping caused by PMMA-950k residue and a low-residue transfer can be achieved by the use of PMMA-mixture. When graphene was transferred by the supporting of PMMA-mixture, lower error bars (variations) were observed from the statistic results of frequency shift and FWHM of G band, which further implies the less aggregation of PMMA residues because of the p-type doping varied with the size of PMMA-absorbed dopants. The XPS analysis through Gaussiane-Lorentzian intensity fittings of C–C, O–CH3, and O–C=O bond also confirmed the extensive reduction of residue on graphene transferred by supporting layer of PMMA-mixture. The improved transfer process using PMMA-mixture as a supporting layer without thermal treatment can also be applied to the transfer of other 2D materials, which can boost the development of 2D material-based electronic and optoelectronics heterostructural devices.

 Figure 2. Analysis of PMMA residues through X-ray photoelectron spectroscopy

Figure 2. Analysis of PMMA residues through X-ray photoelectron spectroscopy

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