Top-down Fabrication into Sub-nanometre Scale in Low-dimensional Systems

报告题目：Top-down Fabrication into Sub-nanometre Scale in Low-dimensional Systems
报告人:　 Wanlin Guo
报告时间：2014年6月21日上午10：00
报告地点：力学一楼239会议室
　　　　  中国科学院材料力学行为和设计重点实验室

报告人单位：
Key Laboratory of Intelligent Nano Materials and Devices of Ministry of Education, 
State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics, Nanjing, P. R. China.
E-mail: wlguo@nuaa.edu.cn, web:http://nsi.nuaa.edu.cn

报告简介
　  To fabricate functional devices with smaller feature structures in controllable way is always the driven force for our modern industry. The development in industry technologies is propelling the dimension of devices down to 10-nanometers, but facing great challenges in manufacture at sub-10-nanometer scale. Nanotechnology can fabricate nanoribbons from two-dimensional atomic crystals such as graphene well ranged into sub-10-nanometers, but their geometries and properties become hard to control1. Here we analyze the recent breakthrough of top-down technology for fabrication of molybdenum-sulfide ribbons with uniform sub-nanometer width simply by electron irradiation from mechanically exfoliated molybdenum disulfide (MoS2) layer2. This work opened a window to a novel top-down route for controllable fabrication of sub-nanometre building blocks for functional devices, proposing an effective strategy to avoid the limitation of 
lithography resolution. An important novel conception revealed here is that spontaneous phase transition of the irradiated material at sub-nanometre scale is essential for the breakthrough, showing the importance of intrinsic coupling between top-down and bottom-up process. Similar process for creating sub-nanometre wires in other two-dimensional materials will be predicted in this report and new evidences will be introduced. Two-dimensional materials themselves can be obtained through either top-down or bottom-up methodology3, and can bring the exceptional properties at one atomic layer thickness into our macro-world, promising plenty of rooms for technology revolution. For example, we recently found that drawing a droplet over monolayer graphene can induce electric potential, the so called drawing potential4, waving seawater across graphene can generate more electricity5. These novel electrokinetic phenomena are found to be unique to graphene like nanofilms, open route for novel functional devices and energy harvesting6. Exceptional bending Poisson effect is also found in two-dimensional nanomaterials7.

Reference
1.Novoselov, K. S. et al. A roadmap for graphene. Nature 490, 192-200 (2012).
2.Liu, X. ; Sun, L. T. & Guo, W. et al. Top-down fabrication of sub-nanometre semiconducting nanoribbons derived from molybdenum disulfide sheets, Nature Commun. 4, 1776, (2013).
3.Guo, W.; Liu, X. 2D materials: Metallic when narrow. Nature Nanotech. 9, 413 (2014).
4.Li, X.; Yin, J.; Zhou, J. & Guo, W. Large area hexagonal boron nitride monolayer as efficient atomically thick insulating coating against friction and oxidation. Nanotech. 25, 105701. (2013).
5.Yin, J., Li, X., Yu, J., Zhang, Z., Zhou, J. & Guo, W. Generating electricity by moving a droplet of ionic liquid along graphene. Nature nanotechnology 9 (5), 378-383 (2014).
6.Yin, J. & Guo et al. Waving potential in graphene. Nature communications 5,  3582 (2014). http://nanotechweb.org/cws/article/tech/57149
7.Li, X.; Pan, D.; Hong, Y.; Guo, W. Bending Poisson effect in two-dimensional crystals. Physical Review Letters 112 (20), 205502 (2014)。
 

报告人简介：
Wanlin GUO, Ph.D. Professor in Mechanics and Nanoscience Director of Institute of Nano Science in Nanjing University of Aeronautics nd Astronautics (NUAA);
Director of Key Laboratory of Intelligent Nano Materials and Devices of MoE in NUAA;Deputy Director of State Key Laboratory of Mechanics and Control of 
Mechanical Structures in NUAA; In 1981-1991, He studied Aerospace Engineering and solid mechanics in Northwestern Ploytechnical University and obtained his Master and PhD degrees in solids mechanics with the best academic records. From 1991-2002 he has worked as Post-D, associated professor and professor in Xian Jiaotong University. In 1995-1998, he worked at the Center-of-Expertise of Australian Defence Science and Technology Organization at Monash University. He 
obtained the Outstanding Young Scientist Award (Premier Fund) of China in 1996 and the honor of Cheung Kong Scholars in 1999 and worked as Chair Professor in Nanjing University of Aeronautics and Astronautics since 2000. In 2005, he leaded a team in Nano-scale Physical Mechanics enters the Cheung Kong Scholars Excellent Team Programme of the Ministry of Education of China. In 2010, he founded the Key Laboratory of Intelligent Nano Materials and Devices of the Ministry of Education of China. His current research interests cover intelligent nano materials and devices, high efficient energy conversion nanotechnology, three dimensional fatigue fracture and damage tolerance and durability of mechanical structures. He has published 300+ refereed papers in mechanics-related journals such as Nature Nanotech, Nature Comm. Phys. Rev. Lett., Nano Lett., J. Am. Chem. Soc. Adv. Mater., Small, Nanoscale, J. Mech. Phys. Solids et al.and awarded the 2nd National Prize in Nature Science in 2012 for his contribution to nanomechanics.