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Creating multiple meshes of a semiconductor device by varying specific geometric properties, like the gate length of a MOSFET, is a crucial step for optimization or scaling processes of these devices. A geometry generation technique for semiconductor devices using geometry templates is presented and implemented in the open source meshing tool ViennaMesh, providing a convenient mechanism for creating...
The physical models and algorithms of device simulation for ultra-high speed devices are proposed. The propagation of electromagnetic field induced by electrodes cannot be ignored for analyses of ultra-high speed devices. In order to obtain the consistent basic equations for the both of device and electromagnetic field propagation simulations, we newly introduce Nakanishi-Lautrup (NL) field of quantum...
If the trap density is 1012 cm−2, then there are only one trap in 10nm × 10nm on average. Accordingly, three-dimensional simulation that is sensitive to the movement of sole electron is indispensable for carefully investigating the reliability issues related to local traps in future nano-electron devices. As a demonstration, we investigate Random Telegraph Noise (RTN) and Trap-Assisted Tunneling (TAT)...
In this paper, we present a study of the self-heating effects in GaN-based power devices during static and dynamic operation mode by means of Sentaurus TCAD. A physical model interface (PMI), accounting for the temperature dependence of the thermal boundary resistance (TBR), has been implemented in the simulator in order to realistically model self-heating effects. In particular, we take into account...
We report on our development of a Silicon Carbide Power System Computer Aided Design Tool to address the need for improved methodologies for developing next generation high efficiency power electronics using Silicon Carbide power devices. The first major achievement is to develop compact models for SiC power MOSFETs and to input these models into CoolCAD's SPICE-type simulator, CoolSPICE (the student...
A three dimensional simulation system for light-illuminated STM measurements is proposed for the first time combining semiconductor process and device simulators with an FDTD solver. Photo-generation rates estimated from light intensity obtained from the FDTD solver are incorporated into a semiconductor device simulation of a device structure including a semiconductor sample and an STM probe tip....
This paper studies, through Three-Dimensional (3D) TCAD simulations, the formation of gate edge pits on the drain-side of GaN high electron mobility transistors (HEMTs) under electrical stress conditions. These pits are believed to be formed due to electrochemical reactions. The simulations predict that holes, which are necessary to initiate the electrochemical reaction but rare under regular HEMT...
A physical compact charge carrier mobility model for undoped-body organic thin-film transistors (OTFTs) based on an analysis of the bias-dependent Fermi-energy movement in the band gap is reported. Mobility in localized- and extended-energy states predicts the current transport in week- and strong-inversion regimes, respectively. A hopping mobility model as a function of surface potential is developed...
The Wigner equation can conveniently describe quantum transport problems in terms of particles evolving in the phase space. Improvements in the particle generation scheme of the Wigner Monte Carlo method are shown, which increase the accuracy of simulations as validated by comparison to exact solutions of the Schrödinger equation. Simulations with a time-varying potential are demonstrated and issues...
In the course of years, several models have been put forward to explain noise phenomena, bias temperature instability (BTI), and gate leakage currents amongst other reliability issues. Mostly, these models have been developed independently and without considering that they may be caused by the same physical phenomenon. However, new experimental techniques have emerged, which are capable of studying...
We present and validate a novel physics-based model for hot-carrier degradation. The model incorporates such essential ingredients as a superposition of the multivibrational bond dissociation process and single-carrier mechanism, dispersion of the bond-breakage energy, interaction of the electric field and the dipole moment of the bond, and electron-electron scattering. The main requirement is that...
In this paper, a realistic atomic model is used to study the atomic ordering effect on electronic structures of Si0.5Ge0.5. The hybrid density functional theory (DFT), HSE06, is chosen as the methodology. The calculated bandgap and effective masses of Si and Ge at various symmetry points are first validated by the reported experimental data and empirical pseudo-potential method (EPM) calculations...
A comprehensive time dependent three dimensional simulation framework for high-k degradation is developed. In this framework, the models that account for trap generation in high-k, capture/emission dynamic, and statistical variability are incorporated in the simulation. The influence of the trap generation model on distribution of traps, threshold voltage, and the amount of trapped charge is investigated...
We report a milestone in device modeling whereby a planar MOSFET with extremely thin silicon on insulator channel is simulated at the atomic level, including significant parts of the gate and buried oxides explicitly in the simulation domain, in ab initio fashion, i.e without material or geometrical parameters. We use the density-functional-based tight-binding formalism for constructing the device...
For the first time, an efficient and universal method to design multiple field limiting rings (FLR) structure, which applicable to power devices with thin drift layer is proposed. Avalanche breakdown simulations of simplified structures are performed in each three area; the near main junction area, the outmost area, and the other. From simulation results, optimal spacing between each neighboring FLR...
Given the rapid recovery of the degradation induced by bias-temperature stress, the understanding and modeling of NBTI has been a challenge for nearly half a century. With the introduction of the time-dependent defect spectroscopy (TDDS), NBTI could be studied at the single defect level, confirming that it is dominated by a collection of first-order reactions rather then the previously invoked reaction-diffusion...
Monolayer transition metal dichalcogenides (TMDs) are novel gapped two-dimensional materials with unique electrical and optical properties. Here, we study the effect of dielectric oxide slabs on the electronic structure of monolayer MoS2 using density functional theory (DFT) calculations. We also have simulated the effects of O-vacancies in the first few layers of the oxide on the band structure of...
New architectures introduction succeeded in reducing the device performances dispersion in scaled transistors, but as a consequence the relative importance of oxide reliability increased. In this work we present original results of charged interface traps impact on bulk, FDSOI and Fin FETs performances. Traps time constants are analyzed and recoverable and permanent degradation proportions are derived...
We present a theoretical study on the temporal current fluctuation in nanowire FET caused by the presence of a single gate oxide trap through the Coulomb interaction. Our calculations based on the scattering theoretical formulation of the current noise showed that the presence of the trap level in the gate insulator gives rise to the enhancement of the noise at a specific gate voltage. The peak position...
Particle-mesh coupling in ensemble Monte Carlo simulations of semiconductor devices results in unphysical self-forces when using unstructured meshes to describe the device geometry. We develop a correction to the driving electric field and show that self-forces can be virtually eliminated on a finite element mesh at a small additional computational cost. The developed methodology is included into...
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