David Esseni
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View article: Operation and Design of Dirac-Source FETs Using Ab Initio Transport Simulations: Subthreshold Swing and Drive Current
Operation and Design of Dirac-Source FETs Using Ab Initio Transport Simulations: Subthreshold Swing and Drive Current Open
This article investigates the operation and design of Dirac-source FETs (DSFETs), by using ab initio transport simulations based on the NEGF formalism, which seems appropriate given the novelty of the physics and of the device architecture…
View article: Unified Memcapacitor-Memristor Memory for Synaptic Weights and Neuron Temporal Dynamics
Unified Memcapacitor-Memristor Memory for Synaptic Weights and Neuron Temporal Dynamics Open
We present a fabricated and experimentally characterized memory stack that unifies memristive and memcapacitive behavior. Exploiting this dual functionality, we design a circuit enabling simultaneous control of spatial and temporal dynamic…
View article: Modelling and Design of Short Channel Ferroelectric FETs with a Metal Interlayer Easing the Multilevel Operation
Modelling and Design of Short Channel Ferroelectric FETs with a Metal Interlayer Easing the Multilevel Operation Open
This work presents a simulation study of a ferroelectric field effect transistor (FeFET), which leverages a metal interlayer to achieve a multilevel operation thanks to the interplay between the ferroelectric polarization and the charge st…
View article: Multilevel Operation in Scaled Back-End-of-Line Ferroelectric FETs With a Metal Interlayer
Multilevel Operation in Scaled Back-End-of-Line Ferroelectric FETs With a Metal Interlayer Open
Multi-level operation, conventionally obtained in ferroelectric devices thanks to a domain-dependent inhomogeneous polarization, poses a big challenge for highly-scaled ferroelectric devices, where the number of ferroelectric domains is dr…
View article: Transfer-Matrix Modeling of the Access Region Resistance in Graphene Based Dirac-Source FETs
Transfer-Matrix Modeling of the Access Region Resistance in Graphene Based Dirac-Source FETs Open
In this paper we first present a model based on the transfer-matrix methodology to describe the ballistic resistance in a graphene p–n junction, and employ the model in Dirac-Source FETs. In fact, the access region of a graphene based Dira…
View article: Sub-60mV/dec Swing and Drive Current in Dirac-Source FETs: A Design Study Based on First-Principle Transport Simulations
Sub-60mV/dec Swing and Drive Current in Dirac-Source FETs: A Design Study Based on First-Principle Transport Simulations Open
By using a modelling framework consisting of NEGF-based ab-initio simulations, we investigate the operation and design of Dirac-Source FETs (DSFETs). First, we discuss some methodological aspects that we found pivotal to observe the sub-60…
View article: Adiabatic leaky integrate and fire neurons with refractory period for ultra low energy neuromorphic computing
Adiabatic leaky integrate and fire neurons with refractory period for ultra low energy neuromorphic computing Open
In recent years, the in-memory-computing in charge domain has gained significant interest as a promising solution to further enhance the energy efficiency of neuromorphic hardware. In this work, we explore the synergy between the brain-ins…
View article: Reducing the spike rate of deep spiking neural networks based on time-encoding
Reducing the spike rate of deep spiking neural networks based on time-encoding Open
A primary objective of Spiking Neural Networks is a very energy-efficient computation. To achieve this target, a small spike rate is of course very beneficial given the event-driven nature of such a computation. A network that processes in…
View article: Adiabatic Leaky Integrate-and-Fire Neurons with Tunable Refractory Period in 180nm CMOS Technology for Ultra-Low Energy Brain-Inspired Neuromorphic Computing
Adiabatic Leaky Integrate-and-Fire Neurons with Tunable Refractory Period in 180nm CMOS Technology for Ultra-Low Energy Brain-Inspired Neuromorphic Computing Open
In recent years, the In-Memory-Computing in charge domain has gained significant interest as a promising solution to further enhance the energy efficiency of neuromorphic hardware. In this work, we explore the synergy between the brain-ins…
View article: Reinterpreting Low Resistance in Sb–MoS<sub>2</sub> Ohmic Contacts by Means of Ab Initio Transport Simulations
Reinterpreting Low Resistance in Sb–MoS<sub>2</sub> Ohmic Contacts by Means of Ab Initio Transport Simulations Open
By using an in-house nonequilibrium Green's function (NEGF)-based ab initio simulator, we investigate the physical mechanisms driving the Sb( )–MoS system to exhibit the lowest reported contact resistance, m, to the 2-D semiconductor Mo…
View article: Comprehensive Analysis of Graphene Geometric Diodes: Role of Geometrical Asymmetry and Electrostatic Effects
Comprehensive Analysis of Graphene Geometric Diodes: Role of Geometrical Asymmetry and Electrostatic Effects Open
A self-consistent Monte Carlo/3-D Poisson simulator has been developed to analyze the current asymmetry in graphene geometric diodes. The model couples ballistic transport in the graphene layer with 3-D electrostatics in the graphene and o…
View article: Modelling and Simulations of Ferroelectric Materials and Ferroelectric-Based Nanoelectronic Devices
Modelling and Simulations of Ferroelectric Materials and Ferroelectric-Based Nanoelectronic Devices Open
This paper provides a brief introduction to the phenomenological aspects of the polarization in ferrroelectric materials, and then an analysis of a few selected topics related to the modelling of ferroelectrics. The description of ferroele…
View article: Analytical Procedure for the Extraction of Material Parameters in Antiferroelectric ZrO<sub>2</sub>
Analytical Procedure for the Extraction of Material Parameters in Antiferroelectric ZrO<sub>2</sub> Open
Here, we present an analytical procedure to extract the anisotropy constants of antiferroelectric (AFE) materials from a few key features of the experimental polarization versus field curves. Our approach is validated for two experimental …
View article: Ohmic Behavior in Metal Contacts to n/p-Type Transition-Metal Dichalcogenides: Schottky versus Tunneling Barrier Trade-off
Ohmic Behavior in Metal Contacts to n/p-Type Transition-Metal Dichalcogenides: Schottky versus Tunneling Barrier Trade-off Open
High contact resistance (RC) between 3D metallic conductors and single-layer 2D semiconductors poses major challenges toward their integration in nanoscale electronic devices. While in experiments the large RC values can be partly due to d…
View article: Bridging Large-Signal and Small-Signal Responses of Hafnium-Based Ferroelectric Tunnel Junctions
Bridging Large-Signal and Small-Signal Responses of Hafnium-Based Ferroelectric Tunnel Junctions Open
Ferroelectric Tunnel Junctions (FTJs) op- erating as memristors are promising electron devices to realize artificial synapses for neuromorphic computing. But the understanding of their operation requires an in-depth electrical characteriza…
View article: Ab-initio transport simulations unveil the Schottky versus Tunneling barrier trade-off in metal-TMD contacts
Ab-initio transport simulations unveil the Schottky versus Tunneling barrier trade-off in metal-TMD contacts Open
We investigate several options for metal contacts to monolayer 2D semiconductors with an in-house developed, ab-initio transport methodology. We identify an optimum separation between the metal and the semiconductor resulting in minimum co…
View article: Multi-level Operation of FeFETs Memristors: the Crucial Role of Three Dimensional Effects
Multi-level Operation of FeFETs Memristors: the Crucial Role of Three Dimensional Effects Open
This paper investigates and compares through a comprehensive TCAD analysis 2D and 3D simulations for ferroelectric based FETs. We provide clear evidence that the multiple read conductance values experimentally observed in FeFETs stem from …
View article: Polarization switching and AC small-signal capacitance in Ferroelectric Tunnel Junctions
Polarization switching and AC small-signal capacitance in Ferroelectric Tunnel Junctions Open
We here report a joint experimental and simulation analysis for large signal P-V and AC small– signal C-V curves in ferroelectric tunnel junctions. The attempt to reproduce both experimental data sets with the same model and material param…
View article: Modeling Approaches for Gain, Noise and Time Response of Avalanche Photodiodes for X-Rays Detection
Modeling Approaches for Gain, Noise and Time Response of Avalanche Photodiodes for X-Rays Detection Open
We report on a suite of modeling approaches for the optimization of Avalanche Photodiodes for X-rays detection. Gain and excess noise are computed efficiently using a non-local/history dependent model that has been validated against full-b…
View article: Accurate Nonlocal Impact Ionization Models for Conventional and Staircase Avalanche Photodiodes Derived by Full Band Monte Carlo Transport Simulations
Accurate Nonlocal Impact Ionization Models for Conventional and Staircase Avalanche Photodiodes Derived by Full Band Monte Carlo Transport Simulations Open
We present a procedure to extract the nonlocal impact ionization coefficients in Avalanche Photodiodes (APDs) operating in the linear regime from Full Band Monte Carlo simulations. The Monte Carlo calculations have been calibrated on exist…
View article: Reducing the Spike Rate in Deep Spiking Neural Networks
Reducing the Spike Rate in Deep Spiking Neural Networks Open
One objective of Spiking Neural Networks is a very efficient computation in terms of energy consumption. To achieve this target, a small spike rate is of course very beneficial since the event-driven nature of such a computation. However, …
View article: Neuromorphic object localization using resistive memories and ultrasonic transducers
Neuromorphic object localization using resistive memories and ultrasonic transducers Open
Real-world sensory-processing applications require compact, low-latency, and low-power computing systems. Enabled by their in-memory event-driven computing abilities, hybrid memristive-Complementary Metal-Oxide Semiconductor neuromorphic a…
View article: Charge-Trapping-Induced Compensation of the Ferroelectric Polarization in FTJs: Optimal Conditions for a Synaptic Device Operation
Charge-Trapping-Induced Compensation of the Ferroelectric Polarization in FTJs: Optimal Conditions for a Synaptic Device Operation Open
In this work, we present a clear evidence, based on numerical simulations and\nexperiments, that the polarization compensation due to trapped charge strongly\ninfluences the ON/ OFF ratio in Hf 0.5 Zr 0.5 O 2 (HZO)-based ferroelectric\ntun…