Wafer-Scale Growth of WSe2 Monolayers Toward Phase-Engineered Hybrid WOx/WSe2 Films with Sub-ppb NOx Gas Sensing by a Low-Temperature Plasma-Assisted Selenization Process

Henry Medina, Jian Guang Li, Teng Yu Su, Yann Wen Lan, Shao Hsin Lee, Chia Wei Chen, Yu Ze Chen, Arumugam Manikandan, Shin Hung Tsai, Aryan Navabi, Xiaodan Zhu, Yu Chuan Shih, Wei Sheng Lin, Jian Hua Yang, Stuart R. Thomas, Bo Wei Wu, Chang Hong Shen, Jia Min Shieh, Heh Nan Lin, Ali JaveyKang L. Wang, Yu Lun Chueh

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)


An inductively coupled plasma (ICP) process was used to synthesize transition metal dichalcogenides (TMDs) through a plasma-assisted selenization process of metal oxide (MOx) at a temperature as low as 250 °C. In comparison with other CVD processes, the use of ICP facilitates the decomposition of the precursors at low temperatures. Therefore, the temperature required for the formation of TMDs can be drastically reduced. WSe2 was chosen as a model material system due to its technological importance as a p-type inorganic semiconductor with an excellent hole mobility. Large-area synthesis of WSe2 on polyimide (30 × 40 cm2) flexible substrates and 8 in. silicon wafers with good uniformity was demonstrated at the formation temperature of 250 °C confirmed by Raman and X-ray photoelectron (XPS) spectroscopy. Furthermore, by controlling different H2/N2 ratios, hybrid WOx/WSe2 films can be formed at the formation temperature of 250 °C confirmed by TEM and XPS. Remarkably, hybrid films composed of partially reduced WOx and small domains of WSe2 with a thickness of ∼5 nm show a sensitivity of 20% at 25 ppb at room temperature, and an estimated detection limit of 0.3 ppb with a S/N > 10 for the potential development of a low-cost plastic/wearable sensor with high sensitivity.

Original languageEnglish
Pages (from-to)1587-1598
Number of pages12
JournalChemistry of Materials
Issue number4
Publication statusPublished - 2017 Feb 28

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry


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