Previously only commercially available in small flakes, the material processed in wafer-scale films could enter the large-scale manufacture of a wide variety of devices including flexible and transparent optoelectronics, gas sensors, memory devices and photovoltaics (PV).
Fabricated using ambient pressure chemical vapour deposition (CVD), the MoS2 films have exceptional carrier mobility and could find their place in the next generation of electronics as silicon reaches its fundamental limits. The MoS2 films, unlike other 2D materials like graphene, enable the emission and detection of light.
By processing initially at room temperature, rather than at the high temperatures typically used (in the region of 800-900ºC), it is possible to deposit MoS2 on a wider range of substrates, namely those with low thermal stability like flexible displays. The technique also minimises stress on other previously deposited layers and helps reduce processing costs.
"Using flakes of MoS2 , which are typically only a few hundred square microns in area, to make devices is impractical time-consuming and inefficient and do not provide a practical route to rapid prototyping and existing semiconductor fabrication protocols.
For these new materials to be adopted in mainstream electronics, they must be compatible with the semiconductor processing lines used in the mass production of electronic chips.", said Dan Hewak, Professor of Optoelectronics at the Zepler Institute.
"Our expertise in novel thin-film fabrication coupled with our ultra-high purity raw material processing facility has enabled us to purify and synthesise large area films to a consistency and purity level not available commercially."
The ambient pressure CVD process that Hewak and his colleagues have developed is an industrially-scalable and controllable deposition methodology and can be used to grow films on a variety of different substrates including plastic.
"We have also developed a technique for lifting these large-area films off the substrate they were grown on and depositing them onto a different substrate," said Hewak.
"This means the films can be put onto any material, opening up entirely new applications."
Hewak and his colleagues are developing processes for the fabrication of a range of transition metal dichalcogenides and are part of the Chalcogenide Advanced Manufacturing Partnership (ChAMP).
ChAMP is an EPSRC-funded partnership between five leading universities and 15 industrial partners dedicated to establishing the UK as a world leader in chalcogenide-glass technology through the development of advanced manufacturing techniques and practical application demonstrations.
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