Rubbing-Induced Site-Selective Patterning for Two-Dimensional Dichalcogenide Devices

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This grant supports research that advances critical knowledge for manufacturing electronic devices based on emerging nanomaterials, helping advance U.S. industrial competitiveness and national prosperity. Two-dimensional nanomaterials, such as transition metal dichalcogenides, could be exploited to make a broad range of electronic and photonic devices with superior functionalities. For example, dichalcogenides such as molybdenum disulfide, can be used to make flexible and wearable devices, biosensors for rapid illness diagnosis, and energy-efficient photodetectors. Although prototypes of these dichalcogenide devices have been demonstrated in the laboratory, the device community still lacks suitable technologies for realizing scalable nanomanufacturing of such devices. One of the most critical challenges is the vulnerability of dichalcogenides to the existing lithography and etching processes for manufacturing electronic devices. This award supports fundamental research to explore imperative knowledge supporting a new manufacturing technology involving site-selective patterning that enables reliable production of dichalcogenide device structures without involving processes that are detrimental to dichalcogenides. The high-quality dichalcogenide device structures produced by this technology are highly desirable for device applications in electronic, sensor, energy storage, and optoelectronic industries. This research enhances participation of underrepresented groups in the education activities related to advanced manufacturing. The new manufacturing technology, termed rubbing-induced site-selective (RISS) patterning, involves a controllable rubbing process for generating nano- or microscale triboelectric charge patterns on a substrate and a subsequent two-dimensional nanomaterial chemical vapor deposition process. The triboelectric charge patterns modulate the nucleation of material deposition precursors on the target substrate and enables direct formation of dichalcogenide device patterns at designated site-selective locations without the need for additional resist-based lithography and plasma etching, which can introduce irreversible contamination and damage to the dichalcogenide layered structure. However, scientific questions need to be answered to make RISS technology practical for manufacturing commercially viable dichalcogenide devices. This research is to understand the mechanisms related to the generation and control of triboelectric charge patterns as well as material deposition processes modulated by electric fields. The research team plans to establish a theoretical-experimental integrated methodology for designing rubbing templates, which can generate high-contrast triboelectric charge patterns under designated mechanical conditions. The research approach is to fabricate rationally designed rubbing templates using focused ion beam and atomic force microscope lithography techniques, experimentally identify mechanical conditions that generate high-contrast triboelectric charge patterns, perform modeling of material diffusion guided by triboelectric field and demonstrate production of arrays of dichalcogenide-based memristive devices for neuromorphic computing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.