Multiscale Patterning And Transfer Printing For Nanogap Device Applications

The multiscale metal micro-nano structure and nanogap is one of the most concerned topics in micro-nano fabrication field.Patterning of metallic nanogap with ultrasmall gap size on arbitrary substrate is of great importance for various applications in nanoelectronics,nanoplasmonics and flexible optoelectronics.However,common lithographic approaches suffer from limited resolution in defining ultrasmall nanogap on specific substrates such as flexible and stretchable substrates and some insulating substrates and rough substrates.In addition,common lithographic approaches are also unable to deal with some substrates and materials incompatible with the lithography process.Therefore,a solution is urgently needed to make up for the shortcomings of ordinary lithography methods.In this work,we propose a process portfolio to overcome the above limits,enabling the fabrication of multiscale metallic nanogaps with reduced gap size on specific substrates for functional devices.The portfolio combines our recently developed“Sketch and peel”lithography strategy,nanotransfer printing and mechanical post-assembly.The portfolio combines our recently developed“Sketch and peel”lithography strategy,nanotransfer printing and mechanical post-assembly.Among the portfolio,the“Sketch and peel”lithography strategy provides unique capability to rapidly and reliably define multiscale adhesion-free metallic nanostructures and nanogaps,which significantly facilitates the subsequent transfer printing process.Nanoplasmonic and nanoelectronic devices with ultrasmall nanogaps that are inaccessible with existing patterning approaches are fabricated to demonstrate the applicability of this fabrication strategy.The portfolio is also supposed to have the potential for a variety of other applications in flexible and stretchable optics,electronics and optoelectronics.The main contents are list as follow:(1)Electron beam“Sketch and Peel”lithography has unique advantages to fabricate multiscale micro-nano structures,and the smallest nanogap is 11nm.Combined with the transfer printing,the scale and precision can be achieved that cannot be fabricated by conventional lithography methods.The fabrication of micro-nano structures on difficult substrates are realized such as curved substrates and flexible substrates.(2)The electron beam“Sketch and Peel”lithography is applied to the preparation of short channel electrodes,and the preparation efficiency is 40 times higher than that of the conventional method.And the short channel MoS2 device with channel length of 70nm is prepared by full dry transfer method,which realized the contact of atomic-level interface and the switching ratio is up to 107.(3)The structures are transferred to the prestretched substrate and released by using nanotransfer printing and mechanical post-assembly technology,and the structure with a sub-5nm gap is prepared.The dimer structures are further transferred to MoS2 material,which enhanced the luminescence response of MoS2 material.The mechanical behavior mechanism is further revealed qualitatively through mechanical simulation.