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Cornell Team Grows Wafer-scale 2D Transition Metal Dichalcogenides

4inch films of monolayer MoS2 and WS2 on insulating SiO2 substrates

A team from Cornell University, New York has reported tuning an MOVCD process to successfully grow wafer-scale, homogenous sheets of the transition metal dichalcogenides MoS2 and WS2

Transition metal dichalcogenides have excellent electrical properties but also a tendency to grown in disjointed, single crystal formations. Smooth, flat, ultrathin sheets, are necessary in order to make practical devices.

Writing in the journal Nature this week, Saien Xie, Kibum Kang and colleagues report the preparation of three-atom-thick, high-mobility 4-inch wafer-scale films of monolayer MoS2 and WS2, grown directly on insulating SiO2 substrates, with excellent spatial homogeneity over the entire films.

They are grown with a newly developed MOCVD technique, and show high electrical performance, including an electron mobility of 30 cm2 V-1 s-1 at room temperature and 114 cm2 V-1 s-1 at 90K for MoS2, with little dependence on position or channel length.

With the use of these films, the researchers say they have successfully demonstrated the wafer-scale batch fabrication of high-performance monolayer MoS2 field-effect transistors with a 99 percent device yield and the multi-level fabrication of vertically stacked transistor devices for three-dimensional circuitry.

The researchers believe that their work is an important step towards the realisation of atomically thin integrated circuitry.

'High-mobility three-atom-thick semiconducting films with wafer-scale homogeneity' by Kibum Kang, Saien Xie et al, Nature 520 (30 April 2015).

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