Project

nano-structures; 2D materials; electronic devices; optoelectronics; spintronics

Lead
La ricerca attuale permette di realizzare cristalli di spessore atomico e di combinarli per fare materiali artificiali, che hanno un potenziale tecnologico enorme per il futuro. La nostra ricerca ha come scopo di studiare questi materiali artificiali e di realizzare dispositivi elettronici che dimostrino il loro potenziale.
Lay summary
Impressionanti sviluppi nel controllo dei materiali permettono di creare e manipolare cristalli di materiali con spessore di uno o pochi atomi (cristalli 2D). Combinando questi cristalli e’ possibile formare interfacce e strutture con nuove  proprieta’, che possono essere considerate come dei veri e propri materiali artificali, le cui caratteristiche sono programmate attraverso la scelta dei cristalli 2D costituenti. Esempi di materiali artificali di questo tipo sono stati dimostrati, ma le possibilita’ da esplorare sono enormi, sia’ perche’ nuovi cristalli 2D vengono continuamente scoperti, sia perche’ le loro combinazioni sono virtualmente infinite. Attualmente, stiamo studiando i principi fisici che permettono di controllare le proprieta’ di materiali artificiali, ottenuti combinando diversi cristalli 2D, con la visione di utilizzarli in applicazioni in dispositivi elettronici del futuro.   A questo scopo realizziamo dispositivi elettronici che permettono di misurare e controllare come gli elettroni si muovono in questi sistemi. Queste misure richiedono l’utilizzo di contatti per potere inviare la corrente e misurare la tensione attraverso i materiali artificiali. La tecnica necessaria per attaccare contatti a cristalli di spessore atomico, come anche per definirne la geometria, e’ la litografia a fascio elettronico. Rimanere competitivi nella nostra ricerca necessita l’utilizzo di un sistema di litografia elettronica di punta e i fondi ottenuti in questo progetto R’Equip, complementati da altrettanti fondi dell’Universita’ di Ginevra, ci permetteranno di acquistare un tal sistema.

Direct link to Lay Summary

Last update: 24.01.2022

Number	Title	Start	Funding scheme

We propose to investigate the electronic properties of different 2D materials by means of experiments that exploit complex artificial nano-structures. 2D materials are crystals that are only one or a few atoms thick. Following the discovery of graphene, a multitude of different 2D materials behaving as semiconductors, insulators, metals, superconductors, ferromagnets, antiferromagnets, topological insulator and more has been produced by micromechanical exfoliation. The properties of these atomically thin systems are distinctly different from those of their bulk parent compounds and can be controlled in unique ways, enabled by their atomic thickness. As a result, research on 2D materials is regularly resulting in new, unexpected discoveries.Our research on 2D material encompasses a broad range of phenomena, including magnetism, gate-induced superconductivity, electron-electron interaction effects in graphene, and the development of new optoelectronic devices. Examples of projects that we will be working on include: i) the control of the band structure of 2D semiconductors by using double ionic gate devices to apply large electric field of unprecedented strength, ii) tunneling spectroscopy -and other related measurements- of gate-induced superconductivity in semiconducting transition metal dichalcogenides, to determine the nature of the superconducting state; iii) the realization of spin filters based on magnetic 2D materials to inject and detect spin-polarized current. These examples are only meant to illustrate the type of research that we will conduct, and many more can be found. Research relies on device structures whose complexity is constantly increasing. Top level results can only be obtained if the nano-fabrication of these structures leads to functioning devices with a sufficiently high yield, which is only possible using state-of-the-art equipment. Our laboratory is equipped with all the needed instrumentation, including glove-boxes with fully automatized stages to controllably transfer 2D materials in a controlled atmosphere. However, our electron-beam lithography system -which has been used continuously since my arrival in Geneva in 2008 and that has allowed research successful at the international level to be carried out- has now reached its limits and is becoming obsolete. Key problems are the system reliability (which seriously lowers the fabrication yield for structures requiring many electron beam lithography steps) and its speed (not sufficient to cope with the many steps required to realize complex structures, nor with the increased number of users). We ask support to purchase a research-level dedicated electron-beam lithography system that will solve these problems. The system will be used by all groups at the Department of Quantum Matter Physics at the University of Geneva (Profs. Baumberger, Renner, and Triscone), which increasingly employ nano-structures in their research: these groups are currently using the existing system installed in my group that -being booked beyond its capacity- is unable to fulfill all requests. The significantly increased speed of the new system will provide enough access time to all users in the department. Additionally, the system will also be used to support collaborative efforts with multiple groups outside Geneva. These include the groups of Prof. Imamoglu (ETH), Maletinsky (Basel), and von Rohr (University of Zurich), which employ structures realized in our laboratory for part of their research. In summary, we ask support for a state-of-the-art electron beam lithography system that will: i) enable our group to carry out research on 2D materials of top international level; ii) drastically improve the research capabilities of all groups at the Department of Quantum Matter in Geneva (including the groups of Professors that will be hired in the near future); iii) have an impact on collaborative research with multiple groups at different Swiss Institutions.