Research Activity

Here an outlook of my research

The continuous downscaling of device geometry has nowadays reached the nanoscale regime, in which device dimensions are of the order of tens of nanometers. Unfortunately such technological solution is no more able to boost transistor performance, but new materials and/or new device concepts have to be pursued instead in order to accomplish this task.

During the last few years, a new class of materials have entered the nanoelectronic scenario, the two-dimesional materials, i.e. materials as thin as one atom. The first one, isolated in 2004 by Novoselov and Geim, is the so-called graphene, i.e., an 2D honey-comb lattice composed by Carbon atoms (Figure below).

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Graphene has shown up to now very large mobilities, impressive mechanical properties, large transparency but unfortunately, it does not possess a bandgap, which makes particularly difficult to use it in digital electronic applications.

While pristine graphene will hardly manage to accomplish the International Technology Roadmap for Semiconductors (ITRS), i.e., the roadmap which provide the guidelines for meeting Industry requirements for next-generation devices, modified graphene can in principle accomplish the goal of obtaining high-performance transistors for the future technological nodes.

For example Graphene nanoribbon, as well as Carbon nanotubes Field Effect Transistors have been demonstrate to possess good performance both for digital and Radio Frequency applications.

Bilayer graphene transistors instead shows poor performance for digital applications, but can be considered as an interesting technological solution for ultra-low power FET (Tunnel FET) and for High-frequency applications.

A lateral heterostructure composed by hexagonal-Boron Nitride and graphene (Figure below), has been proposed and patented in

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order to overcome the issue with the lack of a bandgap in graphene, obtaining large Ion/Ioff ratios and with limited subthreshold swing.

Our reseach is not limited only to graphene, but also to other 2D materials like Bi2Se3 (Figure below), vertical stack of 2D materials and conventional semiconductors, as well as MoS2 transistors.

Bi2Se3_doped

The above-mentioned results have been obtained through the purposely devised physical models, included in the open-source device simulator NanoTCAD ViDES.

The code has allowed us to investigate other materials rather than 2D materials to be exploited in CMOS technology as the ones described below:

Ultra-short channel MOSFETs

Single Electron Transistors and Quantum Point Contacts

Nanocrystal Memories.

Silicon Nanowire Transistors