A. Alarcón

BITLLES: An approach to quantum time-dependent electron transport at the nanoscale

With the aim of manufacturing faster and smaller devices, the electronic industry is today approaching both the nano and the picosecond scales. In this particular scenario, electron dynamics becomes strongly correlated both in space and time. We have recently shown that Bohmian trajectories allow a direct treatment of the time-dependent many-particle interaction among electrons with accuracy comparable to Density Functional Theory techniques. In this work we present a general purpose time-dependent 3D quantum electron transport simulator based on Bohmian trajectories that we call BITLLES. As a numerical example of its capabilities, we compute the full electrical characteristics (DC, High frequency and fluctuations) of a Resonant Tunneling Diode.

Multi-time measurement and displacement current in time-dependent quantum transport

With the aim of manufacturing faster and smaller devices, the electronic industry is today entering into the nanoscale and the high frequency regimes. In this particular scenario, the dynamics of the electron charge becomes affected by quantum mechanical laws, both, for its spatial or temporal description. We have recently shown that Bohmian trajectories allow a direct treatment of the time-dependent many-particle interaction among electrons with an accuracy comparable to Density Functional Theory techniques. In addition, Bohmian mechanics, by combining wave functions and trajectories, provides a very simple description on how to describe multi-time measurements in quantum scenarios. Using the previous formalism, in this work we present a general purpose time-dependent 3D quantum electron transport simulator named BITLLES (Bohmian Interacting Transport in large low-dimensional Electronic Structures) especially indicated for AC, transients and noise predictions. As a numerical example of its capabilities, we compute the full electrical characteristics (DC, High frequency and fluctuations) of a Resonant Tunneling Diode.

Study of the effect of device geometry on the AC behaviour of nanoelectronic devices

The main goal of this work is to study the effect of the structure geometries on the time dependent current in the nano electronic devices. The Ramo-Shockley-Pellegrini theorems are used together with many-particle Monte Carlo simulator to study this problem. In particular, it is shown that when the lateral surfaces (Ly, Lz) where the total current is collected are decreased, while keeping the longitudinal dimension (Lx) fixed, the high frequency range where the AC spectrum is still meaningful increases.

The BITLLES simulator for nanoscale devices

Today, the necessity of faster and smaller devices is pushing the electronic industry into developing electron devices with solid-state structures of few nanometers. In these dimensions electron dynamics are in general governed by quantum mechanical laws. We have recently shown that Bohmian trajectories allow a direct treatment of the many-particle interaction among electrons with an accuracy comparable to DFT techniques. In this article we present a general, versatile and time-dependent 3D quantum electron transport simulator, named BITLLES (Bohmian Interacting Transport in Electronic Structures), based on Bohmian trajectories for nanoelectronic devices. As a numerical example, we show the ability of BITLLES simulator to predict the electrical characteristics (DC, AC and fluctuations) of a Resonant Tunneling Diode.

Electric power in ballistic devices: A reformulation with full Coulomb interaction

An accurate formulation of the electric power in ballistic (classical or quantum) nanoscale devices is presented. The redefinition of the electric power is computed within a many-electron framework (where the dynamic of each electron is determined by its own electric field). The traditional definition of the electric power is compared with the new reformulation presented here for classical double-gate MOSFETs. The accurate results with the many-electron approach show not-negligible discrepancies when compared with the standard definition. Such discrepancies become very important when the single-transistor power is extrapolated to the number of transistors in CPUs.

Quantum instantaneous current: application to nanoMOSFETs switched at very-high frequency

The modeling of nanoscale transistors at THz frequencies is discussed. The simulation of these devices at such very high frequencies can not rely on the assumption that the temporal variations inside the device are slower than any electron kinetic time (i.e. the quasi-static approximation). The study presented here is twofold. First, a novel formalism for quantum transport under oscillating conditions is applied to discuss high-frequency transconductance of nanoscale MOSFET. Second, the importance of the displacement current is analyzed via the solution of a 3D Poisson equation. Preliminary results seem to suggest important effects due to the small number of electrons inside the system.