Coupled quantum-classical transport in silicon nanowires

We present an extended hydrodynamic model describing the transport of electrons in the axial direction of a silicon nanowire. This model has been formulated by closing the moment system derived from the Boltzmann equation on the basis of the maximum entropy principle of Extended Thermodynamics, coupled to the Schr¨odinger-Poisson system. Explicit closure relations for the high-order fluxes and the production terms are obtained without any fitting procedure, including scattering of electrons with acoustic and non polar optical phonons. We derive, using this model, the electron mobility

A statistical enhancement method for Direct Simulation Monte Carlo in semiconductor devices

The Multicomb variance reduction technique has been introduced in the Direct Simulation Monte Carlo for submicrometric semiconductors. We have implemented the method in a silicon diode n+ − n − n+ and demonstrated its effectiveness. The steady-state statistical error and the figures of merit are obtained. The results of the simulations indicate that the method can enhance the high-energy distribution tail with a good accuracy

Ballistic charge transport in a triple-gate silicon nanowire transistor

In this paper we investigate the electrostatics and charge transport in a triplegate Silicon Nanowire transistor. The quantum confinement in the transversal dimension of the wire have been tackled using the Schr¨odinger equation in the Effective Mass Approximation coupled to the Poisson equation. This system have been solved efficiently using a Variational Method. The charge transport along the longitudinal dimension of the wire has been considered using the semiclassical approximation, in the ballistic regime

Monte Carlo and hydrodynamic simulation of a one dimensional n+ – n – n+ silicon diode

An improved closure relation - based on the entropy principle - is implemented in a Hydrodynamic model for electron transport. Steady-state electron transport in the "benchmark" n+ - n - n+ submicron silicon diode is simulated and the quality of the model is assessed by comparison with Monte Carlo results

Elemental fragmentation cross sections for a O-16 beam of 400 MeV/u kinetic energy interacting with a graphite target using the FOOT Delta E-TOF detectors

The study of nuclear fragmentation plays a central role in many important applications: from the study of Particle Therapy (PT) up to radiation protection for space (RPS) missions and the design of shielding for nuclear reactors. The FragmentatiOn Of Target (FOOT) collaboration aims to study the nuclear reactions that describe the interactions with matter of different light ions (like H-1, He-4, C-12, O-16) of interest for such applications, performing double differential fragmentation cross section measurements in the energy range of interest for PT and RPS. In this manuscript, we present the analysis of the data collected in the interactions of an oxygen ion beam of 400 MeV/u with a graphite target using a partial FOOT setup, at the GSI Helmholtz Center for Heavy Ion Research facility in Darmstadt. During the data taking the magnets, the silicon trackers and the calorimeter foreseen in the final FOOT setup were not yet available, and hence precise measurements of the fragments kinetic energy, momentum and mass were not possible. However, using the FOOT scintillator detectors for the time of flight (TOF) and energy loss (Delta E) measurements together with a drift chamber, used as beam monitor, it was possible to measure the elemental fragmentation cross sections. The reduced detector set-up and the limited available statistics allowed anyway to obtain relevant results, providing statistically significant measurements of cross sections eagerly needed for PT and RPS applications. Whenever possible the obtained results have been compared with existing measurements helping in discriminating between conflicting results in the literature and demonstrating at the same time the proper functioning of the FOOT Delta E-TOF system. Finally, the obtained fragmentation cross sections are compared to the Monte Carlo predictions obtained with the FLUKA software

Coupled quantum-classical transport in silicon nanowires

We present an extended hydrodynamic model describing the transport of electrons in the axial direction of a silicon nanowire. This model has been formulated by closing the moment system derived from the Boltzmann equation on the basis of the maximum entropy principle of Extended Thermodynamics, coupled to the Schr¨odinger-Poisson system. Explicit closure relations for the high-order fluxes and the production terms are obtained without any fitting procedure, including scattering of electrons with acoustic and non polar optical phonons. We derive, using this model, the electron mobility

Ballistic charge transport in a triple-gate silicon nanowire transistor

In this paper we investigate the electrostatics and charge transport in a triplegate Silicon Nanowire transistor. The quantum confinement in the transversal dimension of the wire have been tackled using the Schr¨odinger equation in the Effective Mass Approximation coupled to the Poisson equation. This system have been solved efficiently using a Variational Method. The charge transport along the longitudinal dimension of the wire has been considered using the semiclassical approximation, in the ballistic regime