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SISPAD and Technology Computer Aided Design (TCAD) are relatively new compared to semiconductors. The history of using computers to design technology dates to the 60's and the first conferences devoted to the field started in the late 70's. As the field matured, the various conferences combined. TCAD has both benefited from and contributed to Moore's Law. New frontiers in nano-devices, sensors, reliability,...
CMOS technology scaling to decananometer range has raised the challenge to mitigate the impact of multi-scale process variations ranging from cm to atom-scale and acting as circuit yield detractors. Moreover, circuit applications in Ultra Low Power (ULP) range lead to MOSFET device operation in near threshold regime where it is well established that variability impact on DC/AC electrical characteristics...
A deterministic approach for solving the Poisson, Schrödinger and Boltzmann equations in 3D nanoscale devices is presented for the first time, where the Schrödinger equation is included via first order perturbation theory in the Newton-Raphson scheme. The developed solver is shown to be stable even in deep subthreshold simulations, and can provide insight in key phenomena occuring in ultra-short devices...
Good thermoelectric devices with a high value of figure of merit are required to convert back waste heat into useful energy. One way to achieve this goal is to engineer the surface of nanostructures by introducing roughness, thus leading to a significant reduction of their thermal conductivity. We formulate here new theoretical descriptions of phonon interface roughness scattering in Si nanowires...
In this paper, we employ a newly-developed one-dimensional multi-subband Monte Carlo (1DMSMC) simulation module to study electron transport in nanowire structures. The 1DMSMC simulation module is integrated into the GSS TCAD simulator GARAND coupling a MC electron trajectory simulation with a 3D Poisson-2D Schrödinger solver, and accounting for the modified acoustic phonon, optical phonon, and surface...
This simulation work studies whether band-to-band-tunneling leakage in short-channel germanium FinFETs and nanowires can be mitigated by the band gap widening resulting from quantum confinement. Through a combination of drift-diffusion and coupled Poisson-Schrödinger simulations, two possible solutions are investigated: can the BTBT rate be lowered sufficiently? Secondly, can the tunnel path be cut...
Coupled effects of substrate orientation and germanium concentration during silicon-germanium Solid Phase Epitaxial Regrowth (SPER) is analyzed through lattice kinetic Monte Carlo simulations. Atomistic events depending on the bonding environment allow to replicate the effects of alloying on SPER velocity of (100) substrates. The model is then used to draw predictions of the regrowth anisotropy in...
In this work we propose a methodology to analyze the elastic energy interaction at the atomic level between Si self-interstitials and extended defects in crystalline Si. The representation of this energy in maps in 2D planes shows the anisotropic nature of the elastic interaction. This elastic energy maps can be used to understand diffusion trajectories of Si self-interstitials around extended defects...
Impurities being present in a semiconductor in high concentrations may form agglomerates. Agglomeration usually demobilizes the impurities and, in case of dopants, also renders them electrically inactive. A standard approach in continuum process simulation assumes the formation of energetically favorable small clusters of size m. High numbers of m are used to mimic an often desired saturation of the...
Process simulations provide vital insights to identify the key process steps to dedicate wafer resources for improvement or to determine investment on tool capability. We considered this problem in the context of an industry-like 5nm Back-End-of-Line flow being developed in IMEC and modeled the approximately 150 step process flow in COVENTOR SEMulator3D®. For the first time a one-million wafer Design...
A full band Monte Carlo simulation based on ab initio calculations is presented to investigate high-field carrier transport characteristics. The band structure and the impact ionization rate of wide bandgap semiconductors are calculated based on a quasiparticle selfconsistent GW method. Then, we demonstrate the full band Monte Carlo simulation in diamond to investigate the electron and hole ionization...
With the growing interest in III-V-based nano-scale transistors as potential candidates for next-generation switches there is a need for efficient simulation tools capable to predict the impact of inherent quantum effects. In this paper we show how quantum drift-diffusion (QDD) models can be used to mimic those quantum effects. The models do not only properly account for geometrical confinement in...
Computational study of the InP/InGaAs single photon avalanche diode (SPAD) is performed using the additional numerical modeling employed as an extension to the TCAD software. A new simulation environment is employed to model the discrete events such as dark count rate (DCR) and photon detection efficiency (PDE) and is extensively tested for a range of temperatures and 1D structure parameters. DCR...
A novel normally-off AlGaN/GaN HFET (Rake-Gate HFET), based on stress and layout engineering without modifying typical fabrication processes is proposed. It is verified and optimized through TCAD simulation. Positive pinch off voltage is achieved by depositing compressively stressed passivation nitride surrounding gate tines, which induce significant negative piezoelectric charge under the tines....
We present a comprehensive simulation framework for transport modeling in nano-scaled devices based on the solution of the subband Boltzmann transport equation (BTE). The BTE is solved in phase space using a k·p-based electronic structure model and includes all relevant scattering processes. The BTE solver is combined with a conventional drift-diffusion-based simulator using a novel iteration approach...
The peculiar matrix form of the distribution function as the solution to the spinor Boltzmann Transport Equation (S-BTE) has been constructed to address the spin-momentum locking in topological insulators (TIs). Further the hydrodynamic equations with the potential of including spin scattering is derived by taking the momentum moments of the Boltzmann-Vlasov (BV) equation, and is further solved analytically...
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 over several orders of magnitude as a function of gate...
The paper presents a semi-classical model to take into account the effect of field induced as well as geometric quantization. It uses the transfer matrix method to determine whether the energy of a given tunnel path lies above or below the first sub-band level. The validity of the model is verified by simulating transfer characteristics of a one-dimensional InGaAs/GaAsSb n-channel TFET and comparing...
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