Controlled Layer Thinning and p-Type Doping of WSe2 by Vapor XeF2

Rui Zhang, Daniel Drysdale, Vasileios Koutsos, Rebecca Cheung

Research output: Contribution to journalArticlepeer-review

Abstract

This report presents a simple and efficient method of layer thinning and p-type doping of WSe2 with vapor XeF2. With this approach, the surface roughness of thinned WSe2 can be controlled to below 0.7 nm at an etched depth of 100 nm. By selecting appropriate vapor XeF2 exposure times, 23-layer and 109-layer WSe2 can be thinned down to monolayer and bilayer, respectively. In addition, the etching rate of WSe2 exhibits a significant dependence on vapor XeF2 exposure pressure and thus can be tuned easily for thinning or patterning applications. From Raman, photoluminescence, X-ray photoelectron spectroscopy (XPS), and electrical characterization, a p-doping effect of WSe2 induced by vapor XeF2 treatment is evident. Based on the surface composition analysis with XPS, the causes of the p-doping effect can be attributed to the presence of substoichiometric WOx (x < 3) overlayer, trapped reaction product of WF6, and nonstoichiometric WSex (x > 2). Furthermore, the p-doping level can be controlled by varying XeF2 exposure time. The thinning and p-doping of WSe2 with vapor XeF2 have the advantages of easy scale-up, high etching selectivity, excellent controllability, and compatibility with conventional complementary metal-oxide-semiconductor fabrication processes, which is promising for applications of building WSe2 devices with versatile functionalities.
Original languageEnglish
Article number1702455
Number of pages12
JournalAdvanced Functional Materials
Volume27
Issue number41
Early online date13 Sep 2017
DOIs
Publication statusPublished - 3 Nov 2017

Keywords

  • FIELD-EFFECT TRANSISTORS
  • layer thinning
  • p-type doping
  • vapor XeF2
  • WSe2

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