Massimo Fischetti

Massimo Fischetti
The University of Texas at Dallas | UTD · Department of Materials Science & Engineering

PhD

About

327
Publications
49,115
Reads
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15,814
Citations
Additional affiliations
January 1983 - January 2005
IBM Research - Thomas J. Watson Research Center
Position
  • Research Staff Member
August 2010 - present
The University of Texas at Dallas
Position
  • Professor (Full)
Description
  • Quantum Mechanics for Materials Scientists Computational Physics Advanced Physics of Semiconductors: Atomic and electronic structure, and electronic transport Modern Physics II Electromagnetism and Waves
January 2005 - August 2010
University of Massachusetts Amherst
Position
  • Professor (Full)
Education
September 1975 - June 1978
September 1970 - October 1974
University of Milan
Field of study
  • Physics

Publications

Publications (327)
Article
Full-text available
In this theoretical study, we compare electrostatically doped metal-transition metal dichalcogenide (TMD) edge-contacts versus substitutionally doped edge-contacts in terms of their contact resistance. Our approach involves the utilization of electrostatic doping achieved by applying back-gate bias to the metal-TMD edge contacts, where carrier inje...
Article
Oxyhalides form a family of two-dimensional materials with a large bandgap, which makes them interesting for power electronics applications. However, significant research into oxyhalides for use in electronic devices is lacking. Using first principles calculations, we investigate the feasibility of oxyhalides for power transistors. First, we show t...
Article
The present study is concerned with simulating the thermalization of high-energy charge carriers (electrons and/or electron–hole pairs), generated by ionizing radiation, in diamond and β-Ga2O3. Computational tools developed by the nuclear/particle physics and electronic device communities allow for accurate simulation of charge-carrier transport an...
Preprint
The present study is concerned with simulating the thermalization of high-energy charge carriers (electrons and/or electron-hole pairs), generated by ionizing radiation, in diamond and β-Ga2O3. Computational tools developed by the nuclear/particle physics and electronic device communities allow for accurate simulation of charge-carrier transport an...
Article
Since the 1960s and the first observations of radiation-induced disruption of electronic devices in space, the study of the effects of ionizing radiation on electronics has grown into an extensive field of its own. The present paper is concerned with studying accurately the energy-loss processes that control the thermalization of hot carriers (elec...
Article
Scaling electronic devices to the nanometer scale requires, among other constrains, a reduction of the thickness of the channel. This results in quantum confinement of the carriers which, in turn, causes an unavoidable degradation of the charge-transport properties. The advent of graphene seems to have opened a new avenue to circumvent the problem:...
Preprint
The present work is concerned with studying accurately the energy-loss processes that control the thermalization of hot electrons and holes that are generated by high-energy radiation in wurtzite GaN, using an ab initio approach. Current physical models of the nuclear/particle physics community cover thermalization in the high-energy range (kinetic...
Article
Full-text available
Field-effect transistors (FETs) having two-dimensional (2D) materials as the channel offer superior gate control and decreased short-channel effects when compared to bulk-semiconductor channels. Here, employing ab initio band structure and scattering rates as input to Monte Carlo simulations, we investigate the electron-transport characteristics in...
Article
The search for alternatives to Si in the VLSI technology is based on experimental and theoretical work. Here, we consider only the latter and, looking at a few two-dimensional materials of current interest, we use them as examples to emphasize the difficulties faced by theorists in assessing their potential: Silicene and germanene are examples of m...
Article
Full-text available
The performance of transistors based on two-dimensional (2D) materials is affected largely by the contact resistance due to high Schottky barriers at the metal-2D-material interface. In this work, we incorporate the effect of surrounding dielectrics and image-force barrier-lowering in calculating the resistance of Schottky edge-contacts between a m...
Article
We discuss the effect of the dielectric environment (substrate/bottom oxide, gate insulator, and metal gates) on electronic transport in two-dimensional (2D) transition metal dichalcogenides (TMD) monolayers. We employ well-known ab initio methods to calculate the low-field carrier mobility in free-standing layers and use the dielectric continuum a...
Article
We investigate theoretically the impact of the dielectric environment on electronic transport in transition metal dichalcogenide monolayers. The low-field carrier mobility in free-standing layers is calculated using well-known ab initio methods, and the study is extended to layers in double-gate structures using the dielectric continuum approximati...
Article
We compare the image-force barrier lowering (IFBL) and calculate the resulting contact resistance for four different metal–dielectric-two-dimensional (2D) material configurations. We analyze edge contacts in three different geometries (a homogeneous dielectric throughout, including the 2D layer; a homogeneous dielectric surrounding the 2D layer, bo...
Preprint
We discuss the effect of the dielectric environment (insulators and metal gates) on electronic transport in two-dimensional (2D) transition metal dichalcogenides (TMD) monolayers. We employ well-known ab initio methods to calculate the low-field carrier mobility in free-standing layers and use the dielectric continuum approximation to extend our st...
Article
Energetic carriers in semiconductors thermalize by impact-ionization, which generates electron–hole pairs (EHPs), and by energy losses to phonons. The average EHP creation energy is typically about three times the energy gap. In 1960, Shockley derived a simple equation for the average EHP creation energy with a single free parameter that fits exper...
Article
The energy distributions of electrons in gate-all-around (GAA) Si MOSFETs are analyzed using full-band 3-D Monte Carlo (MC) simulations. Excellent agreement is obtained with experimental current-voltage characteristics. For these 24-nm gate length devices, the electron distribution features a smeared energy peak with an extended tail. This extensio...
Article
Full-text available
Over the last few years, ab initio methods have become an increasingly popular tool to evaluate intrinsic carrier transport properties in 2D semiconductors. The lack of experimental information, and the progress made in the development of DFT tools to evaluate electronic band structures, phonon dispersions, and electron–phonon scattering matrix-ele...
Article
Full-text available
We present a theoretical study of the effect of defects on the charge-transport properties of gate-all-around graphene nanoribbons field-effect transistors. Electronic transport is treated atomistically using an efficient method we have recently proposed that makes use of a Bloch-wave basis obtained from empirical pseudopotentials and solves the Sc...
Article
Full-text available
Experimental studies on two-dimensional (2D) materials are still in the early stages, and most of the theoretical studies performed to screen these materials are limited to the room-temperature carrier mobility in the free-standing 2D layers. With the dimensions of devices moving toward nanometer-scale lengths, the room-temperature carrier mobility...
Conference Paper
We find a fundamental limit of channel-length scaling for Laterally Diffused Metal-Oxide-Semiconductor (LDMOS) FETs. We optimize a set of devices with different channel lengths, from 10 nm to 100 nm, through an optimization algorithm to meet a predetermined criterion for drain-to-source subthreshold leakage-current and breakdown voltage. We identif...
Preprint
Full-text available
Experimental studies on two-dimensional (2D) materials are still in the early stages, and most of the theoretical studies performed to screen these materials are limited to the room-temperature carrier-mobility in the free standing 2D layers. With the dimensions of devices moving towards nanometer-scale lengths, the room-temperature carrier-mobilit...
Article
To investigate inelastic electron scattering, which is ubiquitous in various fields of study, we carry out ab initio study of the real-time dynamics of a one-dimensional electron wave packet scattered by a hydrogen atom using different methods: the exact solution, the solution provided by time-dependent density functional theory (TDDFT), and the so...
Preprint
To investigate inelastic electron scattering, which is ubiquitous in various fields of study, we carry out ab initio study of the real-time dynamics of a one-dimensional electron wave packet scattered by a hydrogen atom using different methods: the exact solution, the solution provided by time-dependent density functional theory (TDDFT), and the so...
Article
We study ballistic and dissipative quantum transport of electrons in realistic semiconductor devices. Ballistic electron transport is modeled by solving self-consistently the Schrödinger and Poisson equations in the two-dimensional plane of the device using the effective-mass approximation. The quantum transmitting boundary method (QTBM) is used to...
Article
Full-text available
The absence of a band gap in graphene makes it of minor interest for field-effect transistors. Layered metal chalcogenides have shown great potential in device applications thanks to their wide bandgap and high carrier mobility. Interestingly, in the ever-growing library of two-dimensional (2D) materials, monolayer InSe appears as one of the new pr...
Preprint
Full-text available
Over the last few years, $ab~initio$ methods have become an increasingly popular tool to evaluate intrinsic carrier transport properties in 2D materials. The lack of experimental information, and the progress made in the development of DFT tools to evaluate electronic band structures, phonon dispersions, and electron-phonon scattering matrix-elemen...
Article
Full-text available
The simulation of charge transport in ultra-scaled electronic devices requires the knowledge of the atomic configuration and the associated potential. Such “atomistic” device simulation is most commonly handled using a tight-binding approach based on a basis-set of localized orbitals. Here, in contrast to this widely-used tight-binding approach, we...
Article
Using first-principles calculations we have previously shown that placing graphene on a (111)-oriented perovskite SrTiO3 (STO) surface provides a possible doping mechanism [D. Shin and A. A. Demkov, Phys. Rev. B 97, 075423 (2018)]. Further theoretical analysis presented here suggests that coupling of electrons in graphene to interfacial hybrid plas...
Article
Full-text available
Silicane, a hydrogenated monolayer of hexagonal silicon, is a candidate material for future complementary metal-oxide-semiconductor technology. We determined the phonon-limited mobility and the velocity-field characteristics for electrons and holes in silicane from first principles, relying on density functional theory. Transport calculations were...
Article
Theoretical studies of heat generation and diffusion in Si devices generally assume that hot electrons in Si lose their energy mainly to optical phonons. Here, we briefly review the history of this assumption, and using full-band Monte Carlo simulations—with electron-phonon scattering rates calculated using the rigid-ion approximation and both empir...
Article
High-electron-mobility transistors (HEMTs) based on AlxGa1−xN/GaN heterostructures have great potential for applications in power electronics and radio frequency applications. Operating under large bias and electric fields, hot electrons are present in the channel where they can activate preexisting benign defects that cause scattering or carrier t...
Preprint
The simulation of charge transport in ultra-scaled electronic devices requires the knowledge of the atomic configuration and the associated potential. Such "atomistic" device simulation is most commonly handled using a tight-binding approach based on a basis-set of localized orbitals. Here, in contrast to this widely used tight-binding approach, we...
Article
We investigate the diffusive electron-transport properties of charge-doped graphene ribbons and nanoribbons with imperfect edges. We consider different regimes of edge scattering, ranging from wide graphene ribbons with (partially) diffusive edge scattering to ribbons with large width variations and nanoribbons with atomistic edge roughness. For th...
Article
The thermalization process of sub-10 eV charge carriers is examined with treating carrier transport with full-band Monte Carlo simulations. The average energy loss (3.69 eV in Si and 2.62 eV in Ge) required to create a thermalized electron-hole pair, obtained from the simulations, is very close to the experimentally measured radiation-ionization en...
Article
Recent ab initio theoretical calculations of the electrical performance of several two-dimensional materials predict a low-field carrier mobility that spans several orders of magnitude (from 26 000 to 35 cm2 V−1 s−1, for example, for the hole mobility in monolayer phosphorene) depending on the physical approximations used. Given this state of uncer...
Article
The critical role of silicon and germanium in the semiconductor industry, combined with the need for extremely thin channels for scaled electronic devices, has motivated research towards monolayer silicon (silicene) and monolayer germanium (germanene). The lack of horizontal mirror (σh) symmetry in these two-dimensional crystals results in a very s...
Preprint
Full-text available
We investigate the diffusive electron-transport properties of graphene ribbons and nanoribbons with imperfect edges. We treat different regimes of edge scattering, ranging from wide graphene ribbons with (partially) diffusive edge scattering, to ribbons with large width-variations, and nanoribbons with atomistic edge roughness. For the latter, we c...
Article
Full-text available
In two-dimensional crystals that lack symmetry under reflections on the horizontal plane of the lattice (non-$\sigma_{\rm h}$-symmetric), electrons can couple to flexural modes (ZA phonons) at first order. We show that in materials of this type that also exhibit a Dirac-like electron dispersion, the strong coupling can result in electron pairing me...
Preprint
In two-dimensional crystals that lack symmetry under reflections on the horizontal plane of the lattice (non-$\sigma_{\rm h}$-symmetric), electrons can couple to flexural modes (ZA phonons) at first order. We show that in materials of this type that also exhibit a Dirac-like electron dispersion, the strong coupling can result in electron pairing me...
Article
Full-text available
Recent $\textit{ab initio}$ theoretical calculations of the electrical performance of several two-dimensional materials predict a low-field carrier mobility that spans several orders of magnitude (from 26,000 to 35 cm$^{2}$ V$^{-1}$ s$^{-1}$, for example, for the hole mobility in monolayer phosphorene) depending on the physical approximations used....
Article
In the past couple of decades, the theoretical study of two-dimensional (2D) materials that could (hopefully) extend the miniaturization of semiconductor devices beyond the perceived limits of the Si CMOS technology has been affected by two major changes. On the one hand, these new materials are poorly known, so that one must rely almost exclusivel...
Article
We present a theoretical study of the ballistic performance of gate-all-around field-effect transistors (FETs) with channels consisting of armchair-edge graphene nanoribbons (aGNRs) of various widths and silicon nanowires (SiNWs) with square cross sections. We apply an atomistic quantum transport formalism based on empirical pseudopotentials. Our r...
Article
We present a theoretical study of the negative differential transconductance (NDT) recently observed in lateral-quantum-well Si n-channel field-effect transistors [J. Appl. Phys. 118, 124505 (2015)]. In these devices, p+ doping 'pockets' are introduced at the source-channel and drain-channel junctions, thus creating two potential barriers that defi...
Article
Full-text available
Two-dimensional topological insulators (2D TIs) host topologically protected edge-states with excellent transport properties even in the presence of large amounts of imperfections, such as edge roughness or defects. To overcome the challenge of using two-dimensional materials for nanoelectronic devices, we propose 2D TI field-effect transistors (FE...
Conference Paper
We discuss some basic physical properties of electron transport in two-dimensional materials. First, we discuss how the predicted thermodynamic instability of 2D crystals may influence charge transport via the coupling of electrons with acoustic flexural modes. We then review the properties of suspended and supported graphene and its ribbons and co...
Conference Paper
We present first-principles analytical and Monte Carlo simulations of electron transport in silicene and germanene, assuming a long-wavelength cutoff for the acoustic flexural modes (ZA) to control the divergence of the electron/ZA-phonons coupling at small wavevectors. We also consider the electron mobility in phosphorene as an example illustratin...
Conference Paper
We model a field-effect transistor making use of the spin-polarized edge states of two-dimensional topological insulators. To account for scattering while respecting Pauli's exclusion principle and the ballistic limit, we employ the Boltzmann equation. We account for phonon-assisted scattering processes and show that the current can be modulated ov...
Article
We derive a microscopic Poisson equation using the density-density response function. This equation is valid for any realistic potential perturbation and permits the study of dielectric response in nanostructures, especially in 1D nanostructures and quantum dots. We apply this equation to simulate a nanoscale parallel-plate capacitor (nanocapacitor...
Book
This textbook is aimed at second-year graduate students in Physics, Electrical Engineer­ing, or Materials Science. It presents a rigorous introduction to electronic transport in solids, especially at the nanometer scale. Understanding electronic transport in solids requires some basic knowledge of Ham­iltonian Classical Mechanics, Quantum Mechanics...
Chapter
In this chapter we present the basic definition of lattices, crystals, their symmetries, and the concept of reciprocal lattice, on which studies of electronic structure and transport are based. We also give a brief review of how group theory can be used to understand the physical properties of crystals.
Chapter
We set the foundations of the formalism used in following chapters: We first discuss why we need a formulation of Quantum Mechanics that goes beyond the simple single-particle Schrödinger equation. We then review the Lagrangian and Hamiltonian formulation of Classical Mechanics, since this leads to the formal Canonical Quantization, that is, the fo...
Chapter
Going beyond the Hartree and Hartree–Fock approximations, this chapter deals with fluctuations of an electron gas away from the mean-field approximation. Having introduced the basic distinction between collective effects at long wavelength (plasmons) and single-particle interactions at short range, we derive the short-range interparticle scattering...
Chapter
In this chapter, we review in some detail the solutions of Schrödinger’s equation for a single particle in three dimensions. We treat the case of a free particle, a particle in a box, and a particle in the presence of a Coulomb potential, that is, the hydrogen atom. This first part of the chapter is presented using mathematical details that will be...
Chapter
We present various methods used to calculate the band structure of solids: Plane-wave methods; orthogonalized plane waves, which leads to the concept of model potentials and/or pseudopotentials, self-consistent, and empirical; linear combination of atomic orbitals—LCAO or tight-binding; and k ⋅ p perturbation theory. We also present some significan...
Chapter
We present the formal procedure to quantize fields—the many-body problem—starting from the Lagrangian and Hamiltonian formulation of fields and performing the procedure of canonical quantization of systems with an infinite number of degrees of freedom. We apply this procedure to the significant examples of electrons (the Schrödinger field), plasmon...
Chapter
We illustrate the use of empirical pseudopotentials to study the electronic structure of low-dimensional structures. We consider two-dimensional systems, such as thin Si films, hetero-structures, and graphene, and one-dimensional structures, such as carbon nanotubes and Si nanowires.
Chapter
We discuss the dielectric response of a crystal. We consider separately the ionic response and the electronic response in the Random Phase Approximation. We then consider explicitly the interesting limits of the response of an electron gas in three and two dimensions at low temperature, and in the static- and long-wavelength limits.
Chapter
First-order perturbation theory (Fermi’s Golden Rule or the Born approximation) is used to discuss how to calculate the rate at which electrons in a crystal scatter with space- and/or time-dependent perturbations.The case of electrons in three, two, and one dimension(s) is considered in the general case in which the band structure is known from num...
Chapter
Impurity scattering in semiconductors is discussed presenting the Brooks–Herring and Conwell–Weisskopf models. More advanced treatments, such as Ridley’s statistical screening and partial-wave analysis, are also briefly discussed.
Chapter
The electron–phonon interaction is presented in detail starting from its most general formulation, considering nonpolar (deformation potential) and polar (Fröhlich) interactions. The possible way to calculate the nonpolar electron–phonon matrix elements using DFT is discussed and the rigid-ion approximation is developed in detail. The general form...
Chapter
Starting from the Liouville–von Neumann equation of motion for the density matrix of a system of electrons and phonons, we derive a Master Equation valid over short length-scales by treating the phonons as first-order perturbations. In so doing, we show how elusive is the Ansatz required to introduce irreversibility. We then show how the Boltzmann...
Chapter
We present various methods used to solve numerically the Boltzmann transport equation. The moments methods (drift diffusion, hydrodynamic model, energy transport) are first considered. Particle-based methods (Monte Carlo, cellular automata, scattering matrices, and weighted particles method) are then discussed and we conclude with an overview of di...
Chapter
We formulate the problem of understanding the electronic structure of crystals starting from the “exact” Schrödinger equation for the ions and the electrons and introducing the main approximations—namely, the adiabatic and Hartree–Fock approximations—required to reach a single-electron picture. We then discuss qualitatively the main features of the...
Chapter
Electron dynamics in crystals is presented, starting from the envelope approximation of Luttinger and Kohn. We present the acceleration theorem and apply these results to some interesting cases: Si inversion layers, Stark-ladder quantization and Bloch oscillations, Landau levels, and shallow impurity states.
Chapter
This chapter presents the basic elements of Quantum Statistical Mechanics, starting from the definition of the density matrix. Some examples of density matrices are given, before discussing the grand canonical ensemble, the concept of distribution function, and concluding by deriving the Liouville–von Neumann equations of motion for the density mat...
Chapter
Perturbation theory and the dipole approximation are used to derive the electron–photon Hamiltonian, its matrix elements between Bloch states, and the transition rates for electrons absorbing or emitting a photon. The calculation of the absorption spectrum is presented using these results. As an example, we show the energy distribution of carriers...
Chapter
In this chapter we discuss how to treat electronic transport in small structures with a full quantum-mechanical formulation; that is, we introduce the problem of “quantum transport.” We introduce the concept of Green’s functions and see how they are related to the density matrix. In order to find a solution of the transport problem, we consider fir...
Chapter
We present an introduction to Density Functional Theory. We discuss briefly the Kohn–Sham functional, the local density approximation, and some more sophisticated implementations of the theory. We present some computational examples and show how the theory can be used to provide information needed to study electron transport, focusing on the calcul...
Article
We show that the electron mobility in ideal, free-standing two-dimensional `buckled' crystals with broken horizontal mirror ($\sigma_{\rm h}$) symmetry and Dirac-like dispersion (such as silicene and germanene) is dramatically affected by scattering with the acoustic flexural modes (ZA phonons). This is caused both by the broken $\sigma_{\rm h}$ sy...
Chapter
Following investigations into monolayer silicon (silicene) and germanium (germanene), interest has recently been raised towards monolayer tin (“stanene”). In this chapter, we will discuss the interesting features that can be found in monolayer tin compared to the other hexagonal lattices of the group IV elements. Currently, no experimental results...
Article
The scaling of electronic devices has continued unabated for the past 5 decades, despite repeated predictions of the "end of scaling". The "more than Moore" slogan has been, and still is, viewed by industry as a need to explore realistic low-to-medium-risk avenues, some already in production -- such as strained Si/Ge or high-κ dielectrics, some yet...
Article
Several theoretical electronic structure methods are applied to study the relative energies of the minima of the X- and L-conduction-band satellite valleys of InxGa1−xAs with x = 0.53. This III-V semiconductor is a contender as a replacement for silicon in high-performance n-type metal-oxide-semiconductor transistors. The energy of the low-lying va...
Article
We present a formalism to treat quantum electronic transport at the nanometer scale based on empirical pseudopotentials. This formalism offers explicit atomistic wavefunctions and an accurate band structure, enabling a detailed study of the characteristics of devices with a nanometer-scale channel and body. Assuming externally applied potentials th...
Article
A weakly coupled system of two crossed graphene nanoribbons exhibits direct tunneling due to the overlap of the wavefunctions of both ribbons. We apply the Bardeen transfer Hamiltonian formalism, using atomistic band structure calculations to account for the effect of the atomic structure on the tunneling process. The strong quantum-size confineme...
Article
Full-text available
The tunneling current between two crossed graphene ribbons is described invoking the empirical pseudopotential approximation and the Bardeen transfer Hamiltonian method. Results indicate that the density of states is the most important factor determining the tunneling current between small (nm) ribbons. The quasi-one dimensional nature of graphene...
Conference Paper
Full-text available
After performing one-dimensional simulation of electron transport in narrow quantum wires without gate control in Ref [1], [2] using the open boundary-conditions full-band plane-wave transport formalism derived in Ref [3], we now extend the work to simulate three-dimensionally field-effect transistors (FETs) with a gate bias applied and obtain thei...
Conference Paper
The tunneling current between two crossed graphene ribbons is described invoking the empirical pseudopotential approximation and the Bardeen transfer Hamiltonian method. Results indicate that the density of states is the most important factor determining the tunneling current between small (˜nm) ribbons. The quasi-one dimensional nature of graphene...
Conference Paper
An open boundary-conditions full-band quantum transport formalism with a plane-wave basis based on empirical pseudopotentials is used to self-consistently simulate transistors in the sub-1 nm technology node, with one-dimensional silicon nanowires, armchair-edge graphene nanoribbons, and zigzag-edge carbon nanotubes as the channel. The electrostati...
Research
Full-text available
The empirical pseudopotential band-structure of Ge, Si, GaAs, InAs, and In(0.53)Ga(0.47)As is used to compute the impact ionization (pair production) rate for electrons and holes. The constant-matrix-element and Kane's random-k approximations are also employed, to assess the importance of the energy-dependence of the Coulomb matrix element, of mome...
Conference Paper
We discuss why low-dimensionality materials are needed to scale logic devices to the 5 nm gate-length. We discuss the advantages and disadvantages of graphene and graphene nanoribbons, the feasibility of Bose-Einstein condensation in bilayer graphene, and the use of 2D topological insulators, such as halogen-functionalized monolayer tin.