Prof. Wei ZHOU from Nanyang Technological University (Singapore), a Visiting By-Fellow of Churchill College at University of Cambridge, was invited to give an academic presentation entitled ‘‘Maskless Nanofabrication and Surface Nanopatterning with Focused Ion Beam’’ at the School of Mechanical Engineering (SME), Jiangsu University. Prof. Jianzhong Zhou, SME Secretary of the CPC and Director of Institute for Laser Technology, welcomed Prof. Zhou and chaired his presentation. More than 100 attendees (including Prof. Naifei Ren, Dean of the SME) from the SME and other Schools attended this seminar.
During Prof. Zhou’s presentation, he demonstrated the successful use of 30-50 keV Ga+ focused ion beam (FIB) as a one-step maskless and resistless nanofabrication tool for making nanoscale periodic pillars, wells, and gratings. However, the “direct writing” fabrication process might be severely affected by ion-induced self-organization of surface patterns. Prof. Zhou said he studied a wide range of materials (including pure metals, semiconductor elements and compounds) and identified the major causes for the spontaneous formation of surface patterns, including anisotropic surface diffusion (in Sn and Ti), ion-induced nano-explosion (in Ge and GaSb), and severe Ga redeposition (in GaAs, GaSb and GaN). On the one hand, he explored various ways to suppress the spontaneous surface patterns when they were undesirable. On the other hand, he managed to make use of the phenomena to produce self-organized ripples, nano-dots or nano-rods. Prof. Zhou succeeded in putting forward phenomenogical model describing mechanisms of self-organization for some of the nanostructures through monitoring evolution of the surface patterns using in-situ real-time secondary ion and secondary electron imaging. Finally, examples were given on use of the nanostructures for site-specific microscopic analyses of materials and for making a novel plasmonic nano-lens. Prof. Zhou also answered the questions raised by the attendees. The attendees were impressed by Prof. Zhou’s knowledgeable presentation and his academic seriousness.