Giuseppe Iannaccone

Bio: Giuseppe Iannaccone is an academic researcher from University of Pisa. The author has contributed to research in topics: Field-effect transistor & Graphene. The author has an hindex of 45, co-authored 378 publications receiving 10498 citations. Previous affiliations of Giuseppe Iannaccone include Istituto Nazionale di Fisica Nucleare & National Research Council.

Low-Power Wearable ECG Monitoring System for Multiple-Patient Remote Monitoring

Abstract: Many devices and solutions for remote electrocardiogram (ECG) monitoring have been proposed in the literature. These solutions typically have a large marginal cost per added sensor and are not seamlessly integrated with other smart home solutions. Here, we propose an ECG remote monitoring system that is dedicated to non-technical users in need of long-term health monitoring in residential environments and is integrated in a broader Internet-of-Things (IoT) infrastructure. Our prototype consists of a complete vertical solution with a series of advantages with respect to the state of the art, considering both the prototypes with integrated front end and prototypes realized with off-the-shelf components: 1) ECG prototype sensors with record-low energy per effective number of quantized levels; 2) an architecture providing low marginal cost per added sensor/user; and 3) the possibility of seamless integration with other smart home systems through a single IoT infrastructure.

Performance Comparison of Graphene Nanoribbon FETs With Schottky Contacts and Doped Reservoirs

Abstract: We present an atomistic 3-D simulation study of the performance of graphene-nanoribbon (GNR) Schottky-barrier field-effect transistors (SBFETs) and transistors with doped reservoirs (MOSFETs) by means of the self-consistent solution of the Poisson and Schrodinger equations within the nonequilibrium Green's function (NEGF) formalism Ideal MOSFETs show slightly better electrical performance for both digital and terahertz applications The impact of nonidealities on device performance has been investigated, taking into account the presence of single vacancy, edge roughness, and ionized impurities along the channel In general, MOSFETs show more robust characteristics than SBFETs Edge roughness and single-vacancy defect largely affect the performance of both device types

Lateral Graphene–hBCN Heterostructures as a Platform for Fully Two-Dimensional Transistors

Abstract: We propose that lateral heterostructures of single-atomic-layer graphene and hexagonal boron-carbon-nitrogen (hBCN) domains, can represent a powerful platform for the fabrication and the technological exploration of real two-dimensional field-effect transistors. Indeed, hBCN domains have an energy bandgap between 1 and 5 eV, and are lattice-matched with graphene; therefore they can be used in the channel of a FET to effectively inhibit charge transport when the transistor needs to be switched off. We show through ab initio and atomistic simulations that a FET with a graphene-hBCN-graphene heterostructure in the channel can exceed the requirements of the International Technology Roadmap for Semiconductors for logic transistors at the 10 and 7 nm technology nodes. Considering the main figures of merit for digital electronics, a FET with gate length of 7 nm at a supply voltage of 0.6 V exhibits I(on)/I(off) ratio larger than 10(4), intrinsic delay time of about 0.1 ps, and a power-delay-product close to 0.1 nJ/m. More complex graphene-hBCN heterostructures can allow the realization of different multifunctional devices, translating on a truly two-dimensional structure some of the device principles proposed during the first wave of nanoelectronics based on III-V heterostructures, as for example the resonant tunneling FET.

Ultralow-Voltage Bilayer Graphene Tunnel FET

Abstract: In this letter, we propose the bilayer graphene tunnel field-effect transistor (TFET) as a device suitable for fabrication and circuit integration with present-day technology. It provides high I on/I off ratio at ultralow supply voltage, without the limitations in terms of prohibitive lithography and patterning requirements for circuit integration of graphene nanoribbons. Our investigation is based on the solution of the coupled Poisson and Schrodinger equations in three dimensions, within the non-equilibrium Green's function formalism on a tight binding Hamiltonian. We show that the small achievable gap of only few hundreds of millielectronvolts is still enough for promising TFET operation, providing a large I on/I off ratio in excess of 103 even for a supply voltage of only 0.1 V. A key to this performance is the low quantum capacitance of bilayer graphene, which permits to obtain an extremely small subthreshold swing S smaller than 20 mV/dec at room temperature.

Multiscale Modeling for Graphene-Based Nanoscale Transistors

Abstract: The quest for developing graphene-based nanoelectronics puts new requirements on the science and technology of device modeling. It also heightens the role of device modeling in the exploration and in the early assessment of technology options. Graphene-based nanoelectronics is the first form of molecular electronics to reach real prominence, and therefore the role of single atoms and of chemical properties acquires more relevance than in the case of bulk semiconductors. In addition, the promising perspectives offered by band engineering of graphene through chemical modifications increase the role of quantum chemistry methods in the assessment of material properties. In this paper, we review the multiphysics multiscale (MS) approaches required to model graphene-based materials and devices, presenting a comprehensive overview of the main physical models providing a quantitative understanding of the operation of nanoscale transistors. We especially focus on the ongoing efforts to consistently connect simulations at different levels of physical abstraction in order to evaluate materials, device, and circuit properties. We discuss various attempts to induce a gap in graphene-based materials and their impact on the operation of different transistor structures. Finally, we compare candidate devices in terms of integrated circuit performance and robustness to process variability.

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

2D metal carbides and nitrides (MXenes) for energy storage

Abstract: The family of 2D transition metal carbides, carbonitrides and nitrides (collectively referred to as MXenes) has expanded rapidly since the discovery of Ti3C2 in 2011. The materials reported so far always have surface terminations, such as hydroxyl, oxygen or fluorine, which impart hydrophilicity to their surfaces. About 20 different MXenes have been synthesized, and the structures and properties of dozens more have been theoretically predicted. The availability of solid solutions, the control of surface terminations and a recent discovery of multi-transition-metal layered MXenes offer the potential for synthesis of many new structures. The versatile chemistry of MXenes allows the tuning of properties for applications including energy storage, electromagnetic interference shielding, reinforcement for composites, water purification, gas- and biosensors, lubrication, and photo-, electro- and chemical catalysis. Attractive electronic, optical, plasmonic and thermoelectric properties have also been shown. In this Review, we present the synthesis, structure and properties of MXenes, as well as their energy storage and related applications, and an outlook for future research. More than twenty 2D carbides, nitrides and carbonitrides of transition metals (MXenes) have been synthesized and studied, and dozens more predicted to exist. Highly electrically conductive MXenes show promise in electrical energy storage, electromagnetic interference shielding, electrocatalysis, plasmonics and other applications.

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

Abstract: Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

High-mobility transport anisotropy and linear dichroism in few-layer black phosphorus

Abstract: Two-dimensional crystals are emerging materials for nanoelectronics. Development of the field requires candidate systems with both a high carrier mobility and, in contrast to graphene, a sufficiently large electronic bandgap. Here we present a detailed theoretical investigation of the atomic and electronic structure of few-layer black phosphorus (BP) to predict its electrical and optical properties. This system has a direct bandgap, tunable from 1.51 eV for a monolayer to 0.59 eV for a five-layer sample. We predict that the mobilities are hole-dominated, rather high and highly anisotropic. The monolayer is exceptional in having an extremely high hole mobility (of order 10,000 cm(2) V(-1) s(-1)) and anomalous elastic properties which reverse the anisotropy. Light absorption spectra indicate linear dichroism between perpendicular in-plane directions, which allows optical determination of the crystalline orientation and optical activation of the anisotropic transport properties. These results make few-layer BP a promising candidate for future electronics.