Our Nanolab team is working on research in the field of micro/nano-electronics with special emphasis on: energy efficient devices and their integration in circuits and systems to achieve low power electronic functions, Edge AI and IoT smart sensors for real-time small-foot-print applications, phase change and ferroelectric materials for reconfigurable RF and neuromorphic computation, and, novel architectures of silicon qubits for scalable Quantum Computing.
The lab makes important effort to support the sustainability of future electronics platforms at three levels: (1) by contributing to energy efficiency, (2) by prioritizing materials that are abundant on Earth, and, (3) by working and/or developing with non-toxic fabrication processes.
Energy Efficient Devices for Sustainable Electronics
Quantum mechanical tunneling devices, negative capacitance and nano-electro-mechanical Field Effect Transistors
Nanolab initiated in Europe key research projects with industrial and academic partners, on first tunnel FETs (STEEPER: https://cordis.europa.eu/project/id/257267/de E2SWITCH: https://cordis.europa.eu/project/id/619509/de). In 2007 our group was the first one to demonstrate the advantage of high-k gate stacks in double-gate Tunnel FETs. The group has pioneering contributions in the fundamental physics and engineering of tunnel FETs included length scaling, fundamental definition of the threshold voltage, role of local tensile strain and the first complete explanation of Tunnel FET non-linear output characteristics onset. In 2012 Nanolab group proposed the first breakthrough theoretical concept of a millivolt Density-of-States Switch, embodied as Electron-Hole Bilayer Tunnel Professor Ionescu is author of the most cited review paper on Tunnel FETs published in Nature 2011. In his invited presentation at IEDM 2012 he proposed the first roadmaps for tunnel FETs. Prof. Ionescu’s group experimentally demonstrated at IEDM 2008 sub-60mV/dec slopes in organic ferroelectric (PVDF) gate stack FETs, due to Negative-Capacitance at IEDM 2008. Novel insights followed at IEDM 2010 and, for the first time, his group reported S-shape polarization and tunable intrinsic gain in NC-FETs.
Major recognitions in this field include the Keynote Plenary at IEDM and the 2017 Electron Devices Society George E. Smith Award for the paper “Negative Capacitance as Performance Booster for Tunnel FETs and MOSFETs: An Experimental Study” that appeared in the October 2017 issue of Electron Device Letters. Since over 400 articles were published in Electron Device Letters during 2017, the selection of this paper for the award is a strong endorsement of the quality of the work.
In the NEMS field, Prof. Ionescu group has proposed ground-breaking hybrid devices, combining solid-state device and nano-electro-mechanical parts. We extended Nathanson’s resonant gate FET to novel embodiments and applications in abrupt switching to NEM memory and resonators. He and his students invented the concept of multi-gate vibrating-body FET. His group validated the first ever active MEM resonator (patented), cited by EE-Times in December 2008 as a key energy efficient device and later, in IEDM 2009 his group reported self-oscillations in VB-FETs. The vibrating body FET platform supported the European projects NEMSIC for integrated gas sensing and nanotechnology for early cancer detection using junctionless resonators.
In 2015, we introduced the concept of ‘Sensing with Computing Technology’ with liquid gate silicon FinFETs (patent pending), pointing out the sensitivity benefits from a very low subthreshold slope in a journal paper that followed the Best Paper Award at ULIS 2013 Conference. Finally, prof. Ionescu group has some new contributions into the field of Teraherz devices exploiting unique interactions with 2D materials and control of stack complex conductivity.
In 2016, prof. Ionescu received an Advanced ERC (European Research Council) Grant for individual senior scientists in Europe, entitled Milli-Volt Switch Technologies for Energy Efficient Computation and Sensing (‘Milli-Tech’: https://cordis.europa.eu/project/id/695459/de ), to develop a 5-year research programs aiming at 100 millivolt switches and sensors for Internet-of-Things. The Milli-Tech proposal aims at a novel technology platform serving both computation and sensing: electronic switch architectures, called steep slope switches, exploiting new device physics and concepts in emerging 2D materials to achieve operation at voltages below 100 millivolts. Such switches will have a subthreshold slope below 10mV/decade, significantly more abrupt than MOSFET thermal limit of 60mV/decade at room temperature and in great advance to any beyond CMOS switches. The project will develop a technological platform called ‘millivolt technology’ focusing on low power digital and sensing/ analog electronic functions exploiting steep slopes, with the goal of lowering the energy per useful function (computed and sensed bit of information) by a factor of 100x. Such ultra-low operation voltage will contribute to solving major challenges of nanoelectronics such as power issues and it will enable energy efficient super-sensitive sensors for Internet-of-Everything (IoE). Milli-Tech includes fundamental research on new solid-state steep slope device concepts: heterostructure tunnel FETs in 2D Transition-Metal-Dichalcogenides (TMD), 2D Van der Waals super-lattice energy filter switch and hybrid architectures combining two switching principles: band-to-band-tunneling and metal-insulator-transition or negative capacitance in VO2, used as additive technology boosters.
In 2017, Prof. Ionescu (EPFL) became the scientific coordinator of a FET Open project: Phase-Change Materials and Switches (https://cordis.europa.eu/project/id/737109 ) for Enabling Beyond-CMOS Energy Efficient Applications. Other partners are: AMO GMBH Germany, IBM RESEARCH GMBH, Switzerland, MAX PLANCK, Germany, THALES SA, France, UNIVERSITY OF CAMBRIDGE.
The proposal addressed the need for combined energy efficiency and extended functionality with the engineering of new classes of solid-state Beyond CMOS switches exploiting the abrupt phase-change (Metal-Insulator-Transition – MIT) in materials and at temperatures that make them interesting for electronic circuits and systems by their performance, energy efficiency and scalability. The proposal included disruptive research contributions on the whole value chain, from novel phase-change materials to new device and circuit architectures together with their scaling and integration on silicon and GaN platforms. A significant advance is the three-terminal energy efficient phase-change electronic switch with deep-sub-thermionic average slope (<10mV/decade at room temperature), operating at sub-0.5V voltage supply. The proposal focused on smart design and exploitation of the unique properties of the phase-change VO2 beyond CMOS switches, by targeting with the same technology platform: (i) von-Neumann steep-slope logic devices and circuits, to extend CMOS with novel functionality and energy efficiency, (ii) uniquely reconfigurable energy efficient radio-frequency (RF) circuit functions from 1 to 100GHz, and, (iii) unconventional scalable neuristors exploiting the hysteretic RC switching behavior for neuromorphic computation.
Future Silicon-On-Insulator Qubits for Quantum Computing
In 2020, SNF has confirmed the funding of a new NCCR on Quantum Computing, entitled SPIN (https://www.nccr-spin.ch/ ), aiming at developing silicon qubits that bring magnetic materials on silicon CMOS; Nanolab group is one of the project partners of this very ambitious research that involves the University of Basel (as project leader), ETHZ, EPFL and IBM Research Zürich. Here our work concerns the development of Single Electron Transistors and scalable Silicon-On-Insulator (SOI) Qubits.
Towards Digital Twins at the Edge for Personalized, Preventive and Participator Healthcare
In the currently running FET Proactive DIGIPREDICT (https://www.digipredict.eu/ ) project we proposed the first of its kind digital twin to predict the progression of disease and the need for early intervention in infectious and cardiovascular diseases. A digital twin is a digital representation of an object or process from the real world in the digital world – and more specifically for the case of DIGIPREDICT – of a patient. The project combines the latest advances in digital biomarkers, organ-on-chip (OoC) and artificial intelligence at the edge, and aims to build a new interdisciplinary community in Europe focused on digital twins.
The developed system will provide medical doctors with a unique digital tool for early prediction of potential serious complications in COVID-19 patients. Beyond COVID-19, the system promises to also improve the prevention, diagnosis, monitoring and treatment of cardiovascular disease and detect the potential onset of inflammatory disease.
This multi- and cross-disciplinary project will combine scientific excellence with engineering know-how, and leverage the expertise of doctors, biologists, electrical engineers, computer scientists, signal-processing engineers and social scientists from across Europe.