Electron density control in tungsten diselenide monolayers via photochlorination

Abstract

Modulation of the Fermi level using an ultraviolet (UV)-assisted photochemical method is demonstrated in tungsten diselenide monolayers. Systematic shifts and relative intensities between charged and neutral exciton species indicate a progressive and controllable decrease of the electron density and switch tungsten diselenide from n-type to a p-type semiconductor. The presence of chlorine in the 2D crystal shifts the Fermi level closer to the valence band while the effect can be only partially reversible via continuous wave laser rastering process. The presence of chlorine species in the lattice is validated by X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations predict that adsorption of chlorine on the selenium vacancy sites leads to p-type doping. The results of our study indicate that photochemical techniques have the potential to enhance the performance of various 2D materials, making them suitable for potential applications in optoelectronics.

15 pages, 13 figures

References in corpus (11)

• Two Dimensional Atomic Crystals
• Sequential Edge-Epitaxy in 2D Lateral Heterostructures
• Twistronics: Manipulating the Electronic Properties of Two-dimensional Layered Structures through their Twist Angle
• Anomalous Raman Spectra and Thickness Dependent Electronic properties of WSe2
• Measurement of high exciton binding energy in the monolayer transition-metal dichalcogenides WS2 and WSe2
• Atomically thin mirrors made of monolayer semiconductors
• Relaxation and darkening of excitonic complexes in electrostatically-doped monolayer semiconductors: Roles of exciton-electron and trion-electron interactions
• Family of Two Dimensional Transition Metal Dichlorides Fundamental Properties, Structural Defects, and Environmental Stability
• Exciton spectroscopy and diffusion in MoSe2-WSe2 lateral heterostructures encapsulated in hexagonal boron nitride
• Excitons and trions in monolayer semiconductors with correlated electrons
• $\mathrm{L}{\mathrm{i}}_{\mathrm{x}}({\mathrm{C}}_5{\mathrm{H}}_5\mathrm{N}{)}_{\mathrm{y}}\mathrm{F}{\mathrm{e}}_{2-\mathrm{z}}\mathrm{S}{\mathrm{e}}_2$: a defect resilient expanded-lattice high-temperature superconductor