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.

Design of a 75-nW, 0.5-V subthreshold complementary metal-oxide-semiconductor operational amplifier

Abstract: This work focuses on the subthreshold design of ultra low-voltage low-power operational amplifiers. A well-defined procedure for the systematic design of subthreshold operational amplifiers op-amps is introduced. The design of a 0.5-V two-stage Miller-compensated amplifier fabricated with a 0.18-µm complementary metal-oxide-semiconductor process is presented. The op-amp operates with all transistors in subthreshold region and achieves a DC gain of 70dB and a gain-bandwidth product of 18kHz, dissipating just 75nW. The active area of the chip is i¾?0.057mm2. Experimental results demonstrate that well-designed subthreshold op-amps are a very attractive solution to implement sub-1-V energy-efficient applications for modern portable electronic systems. A comparative analysis with low-voltage, low-power op-amp designs available in the literature highlights that subthreshold op-amps designed according to the proposed design procedure achieve a better trade-off among speed, power, and load capacitance. Copyright © 2013 John Wiley & Sons, Ltd.

Velocity saturation in few-layer MoS2 transistor

Abstract: In this work, we perform an experimental investigation of the saturation velocity in MoS2 transistors. We use a simple analytical formula to reproduce experimental results and to extract the saturation velocity and the critical electric field. Scattering with optical phonons or with remote phonons may represent the main transport-limiting mechanism, leading to saturation velocity comparable to silicon, but much smaller than that obtained in suspended graphene and some III–V semiconductors.

An Ultralow-Voltage Energy-Efficient Level Shifter

Abstract: This brief presents an energy-efficient level shifter (LS) able to convert extremely low level input voltages to the nominal voltage domain. To obtain low static power consumption, the proposed architecture is based on the single-stage differential-cascode-voltage-switch scheme. Moreover, it exploits self-adapting pull-up networks to increase the switching speed and to reduce the dynamic energy consumption, while a split input inverting buffer is used as the output stage to further improve energy efficiency. When implemented in a commercial 180-nm CMOS process, the proposed design can up-convert from the deep subthreshold regime (sub-100 mV) to the nominal supply voltage (1.8 V). For the target voltage level conversion from 0.4 to 1.8 V, our LS exhibits an average propagation delay of 31.7 ns, an average static power of less than 60 pW, and an energy per transition of 173 fJ, as experimentally measured across the test chips.

Physics-based compact model of nanoscale MOSFETs-Part I: transition from drift-diffusion to ballistic transport

Abstract: In this paper, we present a physics-based analytical model for nanoscale MOSFETs that allows us to seamlessly cover the whole range of regimes from drift-diffusion (DD) to ballistic (B) transport, taking into account quantum confinement in the channel. In Part I we focus on MOSFETs with ultrathin bodies, in which quantum confinement is structural rather than field-induced, and investigate in detail an analytical description of the transition from drift-diffusion to B transport based on the Bu/spl uml/ttiker approach to dissipative transport. We first start from the derivation of a closed form analytical expression of the Natori model for B MOSFETs, and show that a MOSFET with finite scattering length can be described as a suitable chain of B MOSFETs. Then, we are able to compact the behavior of the B chain in a simple analytical model. In the derivation, we also find a similarity between the B limit in the chain and the saturation velocity effect, that leads us to propose an alternative implementation of the saturation velocity effect in compact models.

A Semianalytical Model of Bilayer-Graphene Field-Effect Transistor

Abstract: Bilayer graphene has the very interesting property of an energy gap tunable with the vertical electric field. We propose an analytical model for a bilayer-graphene field-effect transistor, suitable for exploring the design parameter space in order to design a device structure with promising performance in terms of transistor operation. Our model, based on the effective mass approximation and ballistic transport assumptions, takes into account bilayer-graphene tunable gap and self-polarization and includes all band-to-band tunneling current components, which are shown to represent the major limitation to transistor operation, because the achievable energy gap is not sufficient to obtain a large Ion/Ioff ratio.

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.