Time-dependent quantum Monte Carlo simulation of electron devices with two-dimensional Dirac materials: A genuine terahertz signature for graphene

Abstract

An intrinsic electron injection model for linear band two-dimensional (2D) materials, like graphene, is presented and its coupling to a recently developed quantum time-dependent Monte Carlo simulator for electron devices, based on the use of stochastic Bohmian conditional wave functions, is explained. The simulator is able to capture the full (DC, AC, transient and noise) performance of 2D electron devices. In particular, we demonstrate that the injection of electrons with positive and negative kinetic energies is mandatory when investigating high frequency performance of linear band materials with Klein tunneling, while traditional models dealing with holes (defined as the lack of electrons) can lead to unphysical results. We show that the number of injected electrons is bias-dependent, implying that an extra charge is required to get self-consistent results. Interestingly, we provide a successful comparison with experimental DC data. Finally, we predict that a genuine high-frequency signature due to a roughly constant electron injection rate in 2D linear band electron devices (which is missing in 2D parabolic band ones) can be used as a band structure tester.

Why engineers are right to avoid the quantum reality offered by the orthodox theory? [point of view]

“…Finally, in the orange solid (triangle) curve, dissipation due to acoustic and optical phonons is considered. This last curve confirms that the electron transport is mainly ballistic [21], [22].…”

“…The blue (square) dashed curve in Fig. 1(b) corresponds to the scenario where electrons are injected from both CB and VB from the zerogap graphene [21], [22]. Contrary to normal transistors, we see in the blue curve that there is no saturation current since applying more voltage between the source and drain leads to more carriers traveling from the source to drain from the VB in the source contact to the CB in the drain contact [23].…”

Noise and charge discreteness as ultimate limit for the THz operation of ultra-small electronic devices

“…Because of their dependence on such external parameter, these states are called conditional states (or conditional wave functions). As explained recently 23,24 , Gambetta and Wiseman 25,26 showed that the physical connection of a property of one conditional states between different times requires a quantum theory (like Bohmian mechanics) where the definition of a conditional state has a clear physical (not only mathematical) meaning. In this work, we will use the BITLLES simulator [27][28][29][30][31][32][33] , developed following this second strategy, to provide numerical support to the conclusions of THz noise in ultra-small electron devices.…”

Stochastic Schrödinger Equations and Conditional States: A General Non-Markovian Quantum Electron Transport Simulator for THz Electronics

“…Specifically, in the BITLLES simulator the first and second terms in Equation ( 16) are evaluated through the solution of the Poisson equation [57]. The third and fourth terms are modeled by a proper injection model [66] as well as proper boundary conditions [56,61,67] that include the correlations between active region and reservoirs. Electron-phonon decoherence effects can be also effectively included in Equation ( 15) [27].…”