Title::Fabrication and characterization of extremely downscaled graphene nanoribborn transistors and nanodot devices

    Speaker:Prof Hiroshi MIZUTA 

    Time: Mar.28,2014 9:30AM

　　Venue:No. 101 Meeting Room, IOS, CAS 

    Graphene is attracting massive worldwide interest for its potential to be the foundation of a new generation of nanoscale integrated devices. This is owing to its remarkable material properties that include very high carrier mobilities and large current carrying capabilities. The carrier mobility in graphene is weakly dependent on temperature which implies the mobility is only limited by impurities and/or defects and hence can be further increased by improving material and device fabrication processes. The electrons in graphene are not much affected by electron – electron interaction and have a long mean free path. In addition, spin-orbit coupling and hyperfine interactions with carbon nuclei are both small in graphene, and a very long spin relaxation length has been demonstrated. All these superior transport properties encourage us to downscale graphene devices further to the regime where we can fully exploit the coherent natures of electronic and spin states. However, this requires the development of ultrafine patterning technologies beyond the present electron-beam (EB) lithography technique. In this talk, I first present our recent attempts of fabricating downscaled graphene nanostructures based on direct milling of graphene using an atomic-size He+ ion beam. I discuss the effects of the He+ ion exposure on the carrier transport properties in a bilayer graphene nanoribbon (GNR) by varying He ion dose, along with underlying carrier scattering mechanisms, along with the theoretical study on the effects of point defects on the carrier transport properties using ab initio simulation, in particular transport gap widening induced by point defects. After that the recent developments of graphene single-carrier transistors based on graphene nanodots (GNDs) and gas molecular detection using GNR transistors are presented.

    Hiroshi Mizuta received the B.S. and M.S. degrees in physics and the Ph.D. degree in electrical engineering from Osaka University, Osaka, Japan. He joined the Central Research Laboratory, Hitachi Ltd., Japan, in 1985, and he has served as the Laboratory Manager and Senior Researcher at the Hitachi Cambridge Laboratory, UK. From 2003 to 2007, he was Associate Professor of Physical Electronics at Tokyo Institute of Technology, Japan, and since 2007 he has been a Professor of Nanoelectronics at NANO Group, Faculty of Physical Sciences and Engineering, University of Southampton, UK. He currently has a joint appointment of Professor at School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST). His current research interests include silicon and graphene nanoelectronics, hybrid nanoelectromechanical systems (NEMS), quantum information technology and ab initio simulation of atomistic devices. He has published more than 400 scientific papers including books and chapters and filed over 50 patents. Dr Mizuta is a member of the Physical Society of Japan, the Japan Society of Applied Physics, the Electron Device Society of the IEEE and Fellow of the Institute of Physics (FInstP). He is an International Advisory Board Member of the MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand.