A New Generation of Ionic Gated Transistors by Prof Alberto Morpurgo

Join us at this IAS STEM Graduate Colloquium by Prof Alberto Morpurgo from the University of Geneva. This talk is in conjunction with the IAS Frontiers Seminars: Quantum Horizons, jointly supported by the Institute of Advanced Studies (IAS) and School of Physical and Mathematical Sciences (SPMS).

About the talk

Ionic gating has been employed very successfully on 2D materials to induce new phenomena, control their electronic properties, and realise proof-of-principle devices. In the vast majority of cases, ionic gating has relied on the use of top ionic liquid electrolytes that cover the gated area of the 2D material of interest. Such a configuration buries the 2D material in between the ionic liquid and the substrate, thereby preventing direct access with many different physical probes that would be useful to investigate the phenomena induced by the gate-accumulated charge density. A solution to this problem requires introducing techniques that enable ionic liquid gating to be performed in a back-gate configuration, capable of leaving the 2D material itself accessible from the top. Over the last few years we have been working to create ionic gated devices that can be operated controllably in a back-gate configuration and we have now succeeded by using so-called Li-ion glass ceramic substrates. In this talk I will discuss the realisation and characterisation of back gated transistors with 2D semiconducting transition metal dichalcogenides based on Li-ion glass substrates, demonstrate ambipolar operation, the ability to reach carrier density in excess of 10¹⁴ cm^-2, and the observation of gate induced superconductivity. I will then present a first type of experiments that are enabled by these new ionic gates, namely the realisation of double-gated ionic transistors allowing the application of perpendicular electric fields larger than 3 V/nm, sufficient to quench the1.6 eV  band gap of bilayer WSe₂. If I have time, I will also briefly discuss experiments in double ionic gate bilayer graphene devices allowing the application of interlayer potential larger than t_perp, a regime never explored earlier. 

About the speaker

Alberto Morpurgo is a condensed matter physicist, with a broad interest in the electronic properties of materials and devices. He received his PhD in 1998 from the University of Groningen (the Netherlands) for his thesis on mescocopic physics, for which he also received the Miedema Prize 1998 for the best Dutch PhD thesis. After a postdoctoral stay at Stanford University, Alberto Morpurgo moved to Delft University, where he became associate professor. In 2008, Alberto Morpurgo moved to University of Geneva, Switzerland, as full professor. The research of Prof Morpurgo has covered a broad variety of material systems (III-V heterostructures, carbon nanotubes, superconductors, organic semiconductors, topological insulators) and physics problems (superconductivity, phase coherent transport, semiconductor physics, electron-electron interaction effects, magnetism etc.). Since the original discovery of graphene, Prof Morpurgo has been working with increasing intensity in the field of 2D materials and heterostructures.