Scalable, top-down optical lithography for electrically contacting monolayer crystallites of vapor grown WSe2 for gas sensing applications

Ideal Ademaj; Thomas Mather; Kishan Jayanand; Anupama B. Kaul

doi:10.1117/12.2632819

3 October 2022 Scalable, top-down optical lithography for electrically contacting monolayer crystallites of vapor grown WSe₂ for gas sensing applications

Ideal Ademaj, Thomas Mather, Kishan Jayanand, Anupama B. Kaul

Author Affiliations +

Proceedings Volume 12200, Low-Dimensional Materials and Devices 2022; 1220009 (2022) https://doi.org/10.1117/12.2632819
Event: SPIE Nanoscience + Engineering, 2022, San Diego, California, United States

Conference Poster

Abstract

Semiconducting two-dimensional transition-metal dichalcogenides (TMDs) have garnered a great deal of interest owing to their large surface-to-volume ratios compared to traditional three-dimensional (3D) semiconductors. One such TMD is tungsten diselenide (WSe₂), which at monolayer (1L) exhibits a direct bandgap and tunable charge transport behavior. This, in combination with its large surface-to-volume ratio, has made WSe₂ a heavily researched material, including for gas sensing applications. However, the synthesis of monolayer WSe₂ has proven to be challenging. In this study, we demonstrate the halide-assisted low-pressure chemical vapor deposition (HA-LPCVD) of high crystalline-quality, monolayer WSe₂. The average synthesized WSe₂ crystallite possessed an edge length of ~ 30 microns. After synthesis, the properties of the WSe₂ membranes were characterized using Raman and photoluminescence spectroscopy. For device fabrication, Cr contacts were deposited atop the WSe₂ membranes using photolithography with a dark-field mask and a metal lift-off process with electron-beam evaporation. After device fabrication, we then proceeded to use these devices for gas sensing applications, where two terminal electronic transport measurements allowed us to monitor the modulation in the WSe₂ transport characteristics with incoming gas flow. The I-V response to target gases N2 and CO2 were recorded to investigate the effects of surface adsorption mechanisms of extrinsic molecules on our material’s conducting behavior.

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Ideal Ademaj, Thomas Mather, Kishan Jayanand, and Anupama B. Kaul "Scalable, top-down optical lithography for electrically contacting monolayer crystallites of vapor grown WSe₂ for gas sensing applications", Proc. SPIE 12200, Low-Dimensional Materials and Devices 2022, 1220009 (3 October 2022); https://doi.org/10.1117/12.2632819

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