Controlled synthesis and transfer of large-area WS2 sheets: From single layer to few layers

Ana Laura Elías, Néstor Perea-López, Andrés Castro-Beltrán, Ayse Berkdemir, Ruitao Lv, Simin Feng, Aaron D. Long, Takuya Hayashi, Yoong Ahm Kim, Morinobu Endo, Humberto R. Gutiérrez, Nihar R. Pradhan, Luis Balicas, Thomas E. Mallouk, Florentino López-Urías, Humberto Terrones, Mauricio Terrones

Research output: Contribution to journalArticlepeer-review

465 Scopus citations


The isolation of few-layered transition metal dichalcogenides has mainly been performed by mechanical and chemical exfoliation with very low yields. In this account, a controlled thermal reduction-sulfurization method is used to synthesize large-area (∼1 cm2) WS2 sheets with thicknesses ranging from monolayers to a few layers. During synthesis, WO x thin films are first deposited on Si/SiO2 substrates, which are then sulfurized (under vacuum) at high temperatures (750-950 C). An efficient route to transfer the synthesized WS2 films onto different substrates such as quartz and transmission electron microscopy (TEM) grids has been satisfactorily developed using concentrated HF. Samples with different thicknesses have been analyzed by Raman spectroscopy and TEM, and their photoluminescence properties have been evaluated. We demonstrated the presence of single-, bi-, and few-layered WS2 on as-grown samples. It is well known that the electronic structure of these materials is very sensitive to the number of layers, ranging from indirect band gap semiconductor in the bulk phase to direct band gap semiconductor in monolayers. This method has also proved successful in the synthesis of heterogeneous systems of MoS2 and WS2 layers, thus shedding light on the controlled production of heterolayered devices from transition metal chalcogenides.

Original languageEnglish (US)
Pages (from-to)5235-5242
Number of pages8
JournalACS nano
Issue number6
StatePublished - Jun 25 2013

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)


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