The first operational amplifier based on a two-dimensional material

Researchers from TU Wien, AMO GmbH, University of Pisa and Wuppertal University have realized the first operational amplifier based on the two-dimensional semiconductor MoS2, reaching a key milestone towards the vision of a flexible electronics all based on two dimensional materials. This result has just appeared in the journal Nature Electronics.

Thanks to its excellent electronic and mechanical properties, the two-dimensional semiconductor MoS2 is a promising material for applications in flexible electronics. These advantages have been already demonstrated mainly at single device level, but so far the variability of the devices hindered the realization of larger and more complex circuits, such as operational amplifiers.

Now, a team of scientists led by Thomas Müller (TU Wien) has demonstrated the first operation amplifier all-based on MoS2. This is a milestone towards real-life applications of two-dimensional (2D) materials, because it demonstrates the high level of reproducibility and the process maturity achieved by MoS2 technology. Indeed, the variability of the MoS2 devices realized by the team of is comparable to that achieved by silicon technology.

Optical microscope image of the operational amplifier based on MoS2

Optical microscope image of the operational amplifier: 64 Operational amplifiers and test devices (left image) and a zoom into one operational amplifier containing 12 MoS2 transistors (right image).

Operational amplifiers are fundamental building block for analog electronics. Numerous functionalities – from simple amplifiers to more complex systems like adders, integrators, differentiators, buffers and filers – can be implemented using the same operational amplifier. From this point of view, operational amplifiers are the crucial element for developing flexible circuits all based on 2D materials, overcoming the actual limitation where sensors based on 2D materials are interfaced with traditional silicon-based components.

“The gain of our operational amplifier is still not as high as in commercial silicon devices”, says Thomas Müller, “but we believe that a more fault-tolerant design, improvements in processing and material quality and, most importantly, the development of CMOS technology in 2D materials will bring it to competitive levels”. The gain of the new operational amplifier is 36 dB, and is the highest value achieved so far using a thin-film-transistor technology, which is the underlying technology in flexible electronics.

The MoS2 operational amplifier is also a milestone for the ORIGENAL project – an Horizon 2020 FET-Open project that aims at achieving a massive 3D-integration of electronic circuits, by folding circuits realized with a thin-film-transistor technology on thin foil substrate. “For flexible and foldable electronics as targeted by ORIGENAL, a high-performance transistor technology is essential to achieve competitive performance parameters.”  says Daniel Neumaier, project coordinator of ORIGENAL. “This work demonstrates that MoS2 is the best available material to realize complex and state-of-the-art circuits using a thin-film-transistor technology as envisioned in our project.”

The work is the result of a collaboration between TU Wien, AMO GmbH, University of Pisa and Wuppertal University.

Bibliographic information:
“Analogue two-dimensional semiconductor electronics”
Dmitry K. Polyushkin Stefan Wachter, Lukas Mennel, Maksym Paliy, Giuseppe Iannaccone, Gianluca Fiori, Daniel Neumaier, Barbara Canto and Thomas Mueller, Nature Electronics (2020).