scholarly journals Monte Carlo Calibrated Drift-Diffusion Simulation of Short Channel HFETs

VLSI Design ◽  
1998 ◽  
Vol 8 (1-4) ◽  
pp. 319-323
Author(s):  
A. Asenov ◽  
S. Babiker ◽  
S. P. Beaumont ◽  
J. R. Barker
Keyword(s):  
Monte Carlo ◽  
Mobility Model ◽  
Channel Length ◽  
Drift Diffusion ◽  
Short Channel ◽  
Velocity Overshoot ◽  
Saturation Velocity ◽  
Mc Simulation ◽  
Diffusion Simulation ◽  
Good Agreement

In this paper we present a methodology to use drift diffusion (DD) simulations in the design of short channel heterojunction FETs (HFETs) with well pronounced velocity overshoot. In the DD simulations the velocity overshoot in the channel is emulated by forcing the saturation velocity in the field dependent mobility model to values corresponding to the average velocity in the channel obtained from Monte Carlo (MC) simulation. To illustrate our approach we compare enhanced DD and MC simulation results for a pseudomorphic HEMTs with 0.12 μm channel length, which are in good agreement. The usefulness of the described methodology is illustrated in a simulation example of self aligned gamma gate pseudomorphic HEMTs. The effect of the gamma gate shape and the self aligned contacts on the overall device performance has been investigated.

scholarly journals Benchmarking of Siemens Linac in Electron Modes: 8-14 MeV Electron Beams

2018 ◽  
Vol 8 (2) ◽  
Author(s):  
H Dowlatabadi ◽  
A A Mowlavi ◽  
M Ghorbani ◽  
S Mohammadi ◽  
F Akbari
Keyword(s):  
Monte Carlo ◽  
Radiation Treatment ◽  
Electron Beams ◽  
Dose Profile ◽  
Depth Dose ◽  
Mcnpx Code ◽  
Gamma Index ◽  
Simulation Results ◽  
Mc Simulation ◽  
Good Agreement

Introduction: Radiation therapy using electron beams is a promising method due to its physical dose distribution. Monte Carlo (MC) code is the best and most accurate technique for forespeaking the distribution of dose in radiation treatment of patients.Materials and Methods: We report an MC simulation of a linac head and depth dose on central axis, along with profile calculations. The purpose of the present research is to carefully analyze the application of MC methods for the calculation of dosimetric parameters for electron beams with energies of 8–14 MeV at a Siemens Primus linac. The principal components of the linac head were simulated using MCNPX code for different applicators. Results: The consequences of measurements and simulations revealed a good agreement. Gamma index values were below 1 for most points, for all energy values and all applicators in percent depth dose and dose profile computations. A number of states exhibited rather large gamma indices; these points were located at the tail of the percent depth dose graph; these points were less used in in radiotherapy. In the dose profile graph, gamma indices of most parts were below 1. The discrepancies between the simulation results and measurements in terms of Zmax, R90, R80 and R50 were insignificant. The results of Monte Carlo simulations showed a good agreement with the measurements. Conclusion: The software can be used for simulating electron modes of a Siemens Primus linac when direct experimental measurements are not feasible.

scholarly journals Validation of the Analytical Model of Oceanic Lidar Returns: Comparisons with Monte Carlo Simulations and Experimental Results

2019 ◽  
Vol 11 (16) ◽  
pp. 1870 ◽  
Author(s):  
Yudi Zhou ◽  
Weibiao Chen ◽  
Xiaoyu Cui ◽  
Aleksey Malinka ◽  
Qun Liu ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Analytical Model ◽  
Oblique Incidence ◽  
Relative Difference ◽  
Experimental Results ◽  
Coefficient Of Determination ◽  
Scattering Approximation ◽  
Angle Scattering ◽  
Mc Simulation ◽  
Good Agreement

The analytical model based on the quasi-single small-angle scattering approximation can efficiently simulate oceanic lidar signals with multiple scattering; thus, its accuracy is of particular interest to scientists. In this paper, the model is modified to include refraction at oblique incidence and is then compared with Monte Carlo (MC) simulations and experimental results. Under different conditions, the results calculated by the analytical model demonstrate good agreement with the MC simulation and experimental data. The coefficient of determination R2 considering the logarithm of signals and the root mean square of the relative difference δ are R2 = 0.998 and δ = 10% in comparison with the semi-analytic MC simulation and R2 = 0.952 and δ = 46% for the lidar experiment. Thus, the results demonstrate the validity of the analytical model in the simulation of oceanic lidar signals.

Ac and Dc Characterization and Spice Modeling of Short Channel Polysilicon Tfts

1996 ◽  
Vol 424 ◽  
Author(s):  
M. D. Jacunski ◽  
M. S. Shur ◽  
T. Ytterdal ◽  
A. A. Owusu ◽  
M. Hack
Keyword(s):  
Frequency Dispersion ◽  
Channel Length ◽  
Short Channel ◽  
Spice Model ◽  
Dc Characteristics ◽  
Physically Based ◽  
In Series ◽  
Drain Bias ◽  
Long Channel ◽  
Good Agreement

AbstractWe present an analytical SPICE model for the AC and DC characteristics of n and p channel polysilicon TFTs which scales fully with channel length and width in all regimes of operation (leakage, subthreshold, above threshold, and kink) and accounts for the frequency dispersion of the capacitance. Once physically based parameters have been extracted from long channel TFTs, which include the gate length and drain bias dependencies of the device parameters, our model accurately reproduces short channel device characteristics. The AC model includes the input channel resistance in series with the gate oxide capacitance. As a result, our model is able to fit the frequency dispersion of the device capacitances. The model has been implemented in the AIM-Spice simulator and good agreement is observed between measured and modeled results for gate lengths down to 4 gim.

Effects of Compositional Segregation and Short Channel on Threshold Voltage of nMOSFET

1997 ◽  
Vol 490 ◽  
Author(s):  
Julie Y. H. Lee ◽  
Tom C. H. Lee ◽  
Mike Embry ◽  
Keenan Evans ◽  
Dan Koch ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Doping Concentration ◽  
Channel Length ◽  
Drift Diffusion ◽  
Short Channel ◽  
Short Channel Effect ◽  
Dopant Segregation ◽  
Channel Effect ◽  
Substrate Doping ◽  
Compositional Segregation

ABSTRACTThis study calculates the threshold voltage (VT) roll-off behavior caused by short channel effect (SCE) as a result of scaling and the reverse short-channel effect (RSCE) due to B segregation around source and drain junctions by using the 2D device simulator - SILVACO™-ATLAS. The simulation results are comparable with the experimental data. It suggests that the drift diffusion physics can predict SCE and RSCE very well to sub-0.25μ Si n-MOSFET devices. The modeling results indicate the VT roll off at shorter channel length for devices with higher substrate doping concentration. VT increases if the local p-dopant segregation exists around the source and drain junction. It is observed that RSCE is more significant for devices with lower substrate doping concentration and shorter channel length.

Carrier Transport and Velocity Overshoot in Strained Si On Sige Heterostructures

1998 ◽  
Vol 533 ◽  
Author(s):  
David K. Ferry ◽  
Gabriele Formicone ◽  
Dragica Vasileska
Keyword(s):  
Monte Carlo ◽  
Enhancement Factor ◽  
Carrier Transport ◽  
State Of The Art ◽  
Carrier Dynamics ◽  
Device Performance ◽  
Short Channel ◽  
Strained Si ◽  
Velocity Overshoot ◽  
Ensemble Monte Carlo

AbstractWe examine the velocity overshoot effect in strained Six on Six-Ge1-x heterostructures. We also investigate the performance of surface-channel strained-Si MOSFETs for devices with gate lengths representative of the state-of-the-art technology. The Ensemble Monte Carlo method, self-consistently coupled with the 2D Poisson equation solver, is used in the investigation of the device performance. Our simulations suggest that, in short-channel devices, velocity overshoot is very important. In fact, when velocity overshoot occurs, it greatly affects the carrier dynamics and the current enhancement factor of both surface-channel strained-Si and conventional Si MOSFETs.

scholarly journals Monte Carlo Simulation of a Submicron MOSFET Including Inversion Layer Quantization

VLSI Design ◽  
1998 ◽  
Vol 6 (1-4) ◽  
pp. 287-290
Author(s):  
J. B. Roldan ◽  
F. Gamiz ◽  
J. A. Lopez-Villanueva ◽  
J. E. Carceller
Keyword(s):  
Monte Carlo ◽  
Inversion Layer ◽  
Channel Length ◽  
Electron Velocity ◽  
Normal Operation ◽  
Electron Dynamics ◽  
Drift Diffusion ◽  
Operation Conditions ◽  
Non Local ◽  
Monte Carlo Simulator

A Monte Carlo simulator of the electron dynamics in the channel, coupled with a solution of the two-dimensional Poisson equation including inversion-layer quantization and drift-diffusion equations has been developed. This simulator has been applied to the study of electron transport in normal operation conditions for different submicron channel length devices. Some interesting non-local effects such as electron velocity overshoot can be observed.

Simulation of Microstructure and Grain Size in Welding Heat Affected Zone Using Monte Carlo Method

2011 ◽  
Vol 194-196 ◽  
pp. 121-126
Author(s):  
Shi Xing Zhang ◽  
Gang Yi Cai
Keyword(s):  
Grain Size ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Kinetic Model ◽  
Grain Growth ◽  
Growth Process ◽  
Great Influence ◽  
Simulation Results ◽  
Mc Simulation ◽  
Good Agreement

In this paper, modeling, procedure and algorithm using Monte Carlo (MC) technology were investigated respectively to simulate grain size and microstructure . First, two different kinetic model were defined by both experimental and statistics method. Then the procedure and algorithm were worked out based on MC technology. Thirdly, the grain growth process in HAZ was simulated, which has great influence on grain growth in HAZ. The result of the simulation demonstrates the grain growth process dynamically. Good agreement between MC simulation results and the experimental results was obtained which can provide a reliable evidence for evaluating the welding craft and the weldability.

scholarly journals Comparison of Single-Particle Monte Carlo Simulation with Measured Output Characteristics of an 0.1µm n-MOSFET

VLSI Design ◽  
2002 ◽  
Vol 15 (4) ◽  
pp. 715-720 ◽  
Author(s):  
F. M. Bufler ◽  
A. Schenk ◽  
C. Zechner ◽  
N. Inada ◽  
Y. Asahi ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Single Particle ◽  
Quantum Effect ◽  
Drain Current ◽  
Linear Regime ◽  
Dopant Distribution ◽  
Electrical Measurements ◽  
Drift Diffusion ◽  
Output Characteristics ◽  
Good Agreement

A comparison between non-selfconsistent single-particle Monte Carlo (MC) simulations and measurements of the output characteristics of an 0.1 µm n-MOSFET is presented. First the bulk MC model, which features a new simplified treatment of inelastic acoustic intravalley scattering, is validated by comparison with experimental literature data for mobilities and velocities. The dopant distribution of the MOSFET is obtained from a 2D process simulation, which is calibrated with SIMS and electrical measurements and fine-tuned by a comparison of the measured transfer characteristics in the subthreshold regime with a coupled Schro¨dinger drift-diffusion (DD) simulation. Then the quantum effect is replaced by a shift of the work function and the DD, hydrodynamic (HD) and MC models are adjusted to reproduce the measured drain current in the linear regime. The results of the three models in the non-linear regime are compared without further adjustment to the measured output characteristics. While good agreement is found for the MC model, the on-current is significantly overestimated by the HD model and underestimated by the DD model.

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