A new technique for fabricating larger amounts of molybdenum disulfide than previously possible could lead to an expanded array of optoelectronic devices.

The technique involves depositing nanoscale MoS₂ thin films on a variety of substrates via atmospheric pressure chemical vapor deposition (APCVD), followed by a two-step annealing process. It was developed by a team from the University of Southampton’s Optoelectronics Research Center.

The APCVD process can be scaled up and easily incorporated with conventional lithography, as the deposition takes place at room temperature, the researchers wrote in a study.

“We have been working on the synthesis of chalcogenide materials using a chemical vapor deposition process since 2001,” said Dr. Kevin Chung-Che Huang, one of the researchers. “And our technology has now achieved the fabrication of large area (>1000 mm²) ultrathin films only a few atoms thick.”

The team also found that “the substrate material plays a significant role in the crystalline structure formation during the annealing process.” They added that single crystalline MoS₂ thin films could be achieved by using both c-plane zinc oxide and sapphire substrates.

MoS₂ could be used in place of graphene thin films in devices such as light sources, transistors and switches. The two substances, which can now both be manufactured in large quantities, share many properties, including very low electrical resistance, extraordinary electronic conduction and mechanical strength.

Unlike graphene, however, MoS₂ can emit light. This could lead to development of enhanced photodetectors, optoelectronic sensors and devices, and potentially thin-film displays.

The work was funded by the Engineering and Physical Sciences Research Council through its Center for Innovative Manufacturing in Photonics.

The research was published in Nanoscale (doi: 10.1039/C4NR04228J).

For more information, visit www.orc.soton.ac.uk.

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