the current semiconductor manufacturing relies heavily on sophisticated fabrication processes such as lithography, vacuum deposition, etc., which may be prohibitively costly and time consuming to adapt to TMDC-based devices. Fortunately, printing technology designed for solution-based low-temperature processing can eliminate the needs for high-cost lithography and vacuum systems. Up to now, printing approaches have been reported for a number of devices including field-effect transistors (FETs), logic gates, and solar cells using carbon nanotubes (CNTs), metal oxides, organic films, or inorganic nanoparticles, which demonstrate the great potential of using printing technology for low-cost and large-scale electronic applications.
We report a three-step “flood-dike” self-aligned printing method which can reliably produce sub-micron channels on 2D TMDC flakes. In this study, we chose CVD-synthesized monolayer WSe2 as the channel materials for demonstration. This printing strategy is highly compatible with other CVD-synthesized, mechanically exfoliated and liquid exfoliated 2D TMDC materials. This “flood-dike” printing method is highly reliable with ~90% yields. The as-printed WSe2 FETs show dramatically improved on-state current densities of ~ 0.64 μA/μm (average), high on/off current ratios of ~ 3x105 (average), and good field-effect mobilities of ~ 1.0 cm2/Vs (average). Compared to previously reported printed 2D TMDC FETs, we have successfully downscaled the channel length to sub-micron scale and promoted the on-state current density by several orders of magnitude. Furthermore, with these superior printed WSe2 transistors, our work offers a lithography-free low-cost platform to produce high-performance 2D TMDC electronics and paves the way for display backplane, sensing and many other potential applications.