Laser-Patterned Submicrometer Bi2Se3–WS2 Pixels with Tunable Circular Polarization at Room Temperature

• Published in: ACS applied materials & interfaces Vol. 14; no. 7; pp. 9504 - 9514
• Main Authors: Hennighausen, Zachariah, Wickramaratne, Darshana, McCreary, Kathleen M, Hudak, Bethany M, Brintlinger, Todd, Chuang, Hsun-Jen, Noyan, Mehmet A, Jonker, Berend T, Stroud, Rhonda M, van ’t Erve, Olaf M
• Format: Journal Article
• Language: English
• Published: American Chemical Society 23.02.2022
• Subjects: Functional Nanostructured Materials (including low-D carbon); transition metal dichalcogenide; photoluminescence; circular polarization; WS2; valleytronics; 2D material; optical data storage
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.1c24205

Characterizing and manipulating the circular polarization of light is central to numerous emerging technologies, including spintronics and quantum computing. Separately, monolayer tungsten disulfide (WS2) is a versatile material that has demonstrated promise in a variety of applications, including single photon emitters and valleytronics. Here, we demonstrate a method to tune the photoluminescence (PL) intensity (factor of ×161), peak position (38.4 meV range), circular polarization (39.4% range), and valley polarization of a Bi2Se3–WS2 2D heterostructure using a low-power laser (0.762 μW) in ambient conditions. Changes are spatially confined to the laser spot, enabling submicrometer (814 nm) features, and are long-term stable (>334 days). PL and valley polarization changes can be controllably reversed through laser exposure in a vacuum, allowing the material to be erased and reused. Atmospheric experiments and first-principles calculations indicate oxygen diffusion modulates the exciton radiative vs nonradiative recombination pathways, where oxygen absorption leads to brightening and desorption to darkening.