Quantum Confinement and Gas Sensing of Mechanically Exfoliated GaSe

Yecun Wu, Duan Zhang, Kangho Lee, Georg S. Duesberg, Askar Syrlybekov, Xiao Liu, Mourad Abid, Mohamed Abid, Yanqi Liu, Lisheng Zhang, Cormac Coileáin, Hongjun Xu, Jiung Cho, Miri Choi, Byong Sun Chun, Haomao Wang, Huajun Liu, Han Chun Wu

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32 Citations (Scopus)


GaSe layers with thicknesses ranging from a monolayer to 100 nm are successfully mechanically exfoliated for use in gas sensing. In combination with density functional theory calculations, general guidelines to determine the number of layers using Raman spectra are presented. With decreasing layer numbers, quantum confinement induces a red-shift for out-of-plane modes and a blue-shift for in-plane modes. The relative Raman shifts of the out-of-plane vibrational modes A1(11) and A1(21) grow exponentially with decreasing stack thickness from 100 to 1 layers. Moreover, the change in first-order temperature coefficient (χ) also increases exponentially as the number of layers is reduced, with the value of the first-order temperature coefficient of the A1(21) mode of monolayer GaSe (≈−1.99 × 10−2 cm−1 K−1) being almost double that of 100 layer GaSe (≈−1.22 × 10−2 cm−1 K−1). Finally, the exfoliated GaSe is used for gas sensing and shows high sensitivity, displaying a minimum detection limit of 4 ppm for NH3 at room temperature, confirming the potential of mechanically exfoliated GaSe in high-sensitivity gas sensors.

Original languageEnglish
Article number1600197
JournalAdvanced Materials Technologies
Issue number1
Publication statusPublished - Jan 2017


  • 2D materials
  • GaSe
  • gas sensing
  • mechanical exfoliation
  • quantum confinement

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Industrial and Manufacturing Engineering


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