Rapid flame synthesis of atomically thin MoO3 down to monolayer thickness for effective hole doping of WSe2

Lili Cai, Connor J. McClellan, Ai Leen Koh, Hong Li, Eilam Yalon, Eric Pop, Xiaolin Zheng

Research output: Contribution to journalArticlepeer-review


Two-dimensional (2D) molybdenum trioxide (MoO3) with mono- or few-layer thickness can potentially advance many applications, ranging from optoelectronics, catalysis, sensors, and batteries to electrochromic devices. Such ultrathin MoO3 sheets can also be integrated with other 2D materials (e.g., as dopants) to realize new or improved electronic devices. However, there is lack of a rapid and scalable method to controllably grow mono- or few-layer MoO3. Here, we report the first demonstration of using a rapid (<2 min) flame synthesis method to deposit mono- and few-layer MoO3 sheets (several microns in lateral dimension) on a wide variety of layered materials, including mica, MoS2, graphene, and WSe2, based on van der Waals epitaxy. The flame-grown ultrathin MoO3 sheet functions as an efficient hole doping layer for WSe2, enabling WSe2 to reach the lowest sheet and contact resistance reported to date among all the p-type 2D materials (∼6.5 and ∼ 0.8 ·μm, respectively). These results demonstrate that flame synthesis is a rapid and scalable pathway to growing atomically thin 2D metal oxides, opening up new opportunities for advancing 2D electronics.

Original languageEnglish (US)
Pages (from-to)3854-3861
Number of pages8
JournalNano letters
Issue number6
StatePublished - Jun 14 2017
Externally publishedYes


  • Flame synthesis
  • MoO monolayer
  • WSe
  • p-type doping
  • transition metal dichalcogenides

ASJC Scopus subject areas

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering


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