Stability – in the sense of stable operation thorough lifetime – is one of the key characteristics that an electronic device need to present to be suitable for applications. And it is the Achilles heel of transistors based on two-dimensional materials, which typically show much worse stability than devices based on silicon. A team of researchers from TU Wien, AMO GmbH, RWTH Aachen University and Wuppertal University has now demonstrated a novel engineering approach to enhance the electrical stability of two-dimensional transistors by carefully tuning the Fermi energy. The results have been reported in Nature Electronics.
Today, there is little doubt that devices based on graphene and other two-dimensional (2D) materials can exceed the state of the art for certain applications, thanks to their intrinsic properties. Two-dimensional materials are also seen as some of the most promising candidates for realizing ultimately scaled transistors at the end of the roadmap of silicon technology. However, devices based on 2D materials often show poor electrical stability, meaning that their behavior changes depending on their operation history.
“Component reliability is one aspect that is often neglected in research, but where we have been working for several years, because it is of central importance for applications.” explains Professor Max Lemme, scientific director of AMO GmbH and Head of the Chair of Electronic Devices at RWTH. The instability is not only caused by 2D materials themselves, but mostly by charges trapped into the oxide-insulator used to fabricate the transistors. “Ideally, one would like to use a different insulator with fewer charge traps,” says Lemme, “but there are no scalable solutions for this yet. In our work, we have shown instead that it is possible to use a standard insulator such as aluminum oxide and to significantly suppress the adverse effects of the charge traps in the oxide, by adjusting the charge carrier density in the 2D material.”
The work combines a thorough theoretical analysis of the novel approach – dubbed by the authors ‘stability-based design’ – and a proof of principle demonstration of the concept, performed by measuring different types of graphene-based FETs. The key idea of the approach is to try to engineer the combination 2D-material/insulator in such a way that the energy of the charge traps in the insulator is as different as possible from the one of the charge carriers in the 2D material. Lemme explains: “Graphene based FETs were the ideal test bed for our approach, as it is relatively easy to tune the energy of charge carriers in graphene. The approach, however, is applicable to all FETs based on 2D semiconductors”. These results represent a major step forward towards stable and reliable 2D materials transistors to be integrated in semiconductor technology.
In a compact comment published in Nature Communications, Max Lemme and colleagues outline the most promising fields of applications of two-dimensional (2D) materials, as well as the challenges that still need to be solved to see the appearance of high-tech products enabled by 2D-materials.[read more »]
Future-shaping concepts such as wearable electronics and the Internet of Things are driving the quest for low-power electronics and for energy harvesting at the device or at chip level. Researchers from AMO GmbH, RWTH Aachen University, Chalmers University and the University of Wuppertal have now developed a novel type of flexible energy harvester, which shows good prospects for powering wearable and conformal devices. [read more »]
One thing that has become clear in the last decade of graphene research is that it is necessary to protect the surface of graphene from external contaminants, to preserve its exceptional electronic properties and be able to exploit them into novel devices. The depositions of dielectric materials on top of graphene is therefore an essential step of manufacturing graphene-based electronic and photonic devices. [read more »]
Two-dimensional (2D) materials have a huge potential for providing devices with much smaller size and extended functionalities with respect to what can be achieved with today’s silicon technologies. But to exploit this potential we must be able to integrate 2D materials into semiconductor manufacturing lines – a notoriously difficult step. A team of researchers from Sweden and Germany now reports a new method to make this work.
Researchers from AMO GmbH, ICFO- Institut de Ciencies Fotoniques, RWTH Aachen University, and Bergishe Universität Wuppertal have developed a novel approach for graphene-based photodetectors that allows combining high responsivity and low power consumption, thus circumventing one of the major limitations of state-of-the-art photodetectors based on graphene – namely the high power-consumption caused by their large dark currents. [read more »]
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.
Max Lemme and co-workers have recently published a review article on nanoelectromechanical (NEMS) sensors based on suspended two-dimensional (2D) materials in the journal RESEARCH, an open-access multidisciplinary journal launched in 2018 as the first journal in the Science Partner Journal (SPJ) program. The paper is an invited contribution to a special issue on “Progress and challenges in emerging 2D nanomaterials – preparation, processing, and device integration”, and has the purpose of contributing to the development of the field of 2D materials for sensor applications and to their integration with conventional semiconductor technology. [read more »]
A review article on one of the most delicate issues of future electronics based on 2D materials
A team of scientists led by Tibor Grasser and Yuri Illarionov of TU Wien, including RWTH Professor and AMO Director Max Lemme, has published an extensive review of the current search for suitable insulators for two-dimensional (2D) nanoelectronics in Nature Communications.