Monte Carlo Modeling of Atom Transport During Directed Vapor Deposition

1996 ◽  
Vol 441 ◽  
Author(s):  
J. F. Groves ◽  
H. N. G. Wadley
Keyword(s):  
Monte Carlo ◽  
Vapor Deposition ◽  
Velocity Vector ◽  
Vapor Transport ◽  
Atomic Vapor ◽  
Collision Model ◽  
Carrier Gas ◽  
Vapor Atom ◽  
The Impact ◽  
Directed Vapor Deposition

AbstractAtomic vapor transport has been investigated in the low vacuum (5 – 100 Pa) supersonic gas jets encountered in directed vapor deposition processes using a combination of Direct Simulation Monte Carlo (DSMC) techniques and a bimolecular collision model. The DSMC code generates the velocity vector, pressure, and temperature field for the carrier gas flow. This data is used as an input to a bimolecular collision model of atomic vapor transport in the flow. In the collision model, calculation of directed momentum loss cross-sections allows the location of carrier gas/vapor atom collisions to be deduced, and the vapor atom velocity vectors for individual vapor atoms to be tracked from source to substrate. For atoms arriving at the substrate, the impact location and velocity vector are obtained, making possible calculation of deposition efficiency, film thickness, adatom energy, and impact angle. These are the key inputs for simulations of resulting film microstructure/morphology evolution. Preliminary results for atomic transport of Cu vapor in supersonic He flows compare favorably with previously reported experimental observations.

Directed Vapor Deposition: Low Vacuum Materials Processing Technology

2000 ◽  
Author(s):  
J. F. Groves ◽  
G. Mattausch ◽  
H. Morgner ◽  
D. D. Hass ◽  
H. N. Wadley
Keyword(s):  
Vapor Deposition ◽  
Processing Technology ◽  
Materials Processing ◽  
Directed Vapor Deposition

scholarly journals The effect of ionic defect interactions on the hydration of yttrium-doped barium zirconate

2021 ◽  
Author(s):  
Sebastian Eisele ◽  
Fabian M. Draber ◽  
Steffen Grieshammer
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
First Principles ◽  
Barium Zirconate ◽  
First Principles Calculations ◽  
Defect Interactions ◽  
The Impact ◽  
Ionic Defect

First principles calculations and Monte Carlo simulations reveal the impact of defect interactions on the hydration of barium-zirconate.

scholarly journals A Monte Carlo Determination of Dose and Range Uncertainties for Preclinical Studies with a Proton Beam

Cancers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1889
Author(s):  
Arthur Bongrand ◽  
Charbel Koumeir ◽  
Daphnée Villoing ◽  
Arnaud Guertin ◽  
Ferid Haddad ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Proton Beam ◽  
Dose Response ◽  
Small Animal ◽  
Absorbed Dose ◽  
Normal Tissue Damage ◽  
Dose Homogeneity ◽  
And Control ◽  
The Impact

Proton therapy (PRT) is an irradiation technique that aims at limiting normal tissue damage while maintaining the tumor response. To study its specificities, the ARRONAX cyclotron is currently developing a preclinical structure compatible with biological experiments. A prerequisite is to identify and control uncertainties on the ARRONAX beamline, which can lead to significant biases in the observed biological results and dose–response relationships, as for any facility. This paper summarizes and quantifies the impact of uncertainty on proton range, absorbed dose, and dose homogeneity in a preclinical context of cell or small animal irradiation on the Bragg curve, using Monte Carlo simulations. All possible sources of uncertainty were investigated and discussed independently. Those with a significant impact were identified, and protocols were established to reduce their consequences. Overall, the uncertainties evaluated were similar to those from clinical practice and are considered compatible with the performance of radiobiological experiments, as well as the study of dose–response relationships on this proton beam. Another conclusion of this study is that Monte Carlo simulations can be used to help build preclinical lines in other setups.

The electron transport that occurs within wurtzite zinc oxide and the application of stress

MRS Advances ◽  
2017 ◽  
Vol 2 (48) ◽  
pp. 2627-2632 ◽  
Author(s):  
Poppy Siddiqua ◽  
Michael S. Shur ◽  
Stephen K. O’Leary
Keyword(s):  
Monte Carlo ◽  
Zinc Oxide ◽  
Electron Transport ◽  
Velocity Field ◽  
Monte Carlo Simulations ◽  
Significant Role ◽  
Energy Gap ◽  
Device Application ◽  
The Impact

ABSTRACTWe examine how stress has the potential to shape the character of the electron transport that occurs within ZnO. In order to narrow the scope of this analysis, we focus on a determination of the velocity-field characteristics associated with bulk wurtzite ZnO. Monte Carlo simulations of the electron transport are pursued for the purposes of this analysis. Rather than focusing on the impact of stress in of itself, instead we focus on the changes that occur to the energy gap through the application of stress, i.e., energy gap variations provide a proxy for the amount of stress. Our results demonstrate that stress plays a significant role in shaping the form of the velocity-field characteristics associated with ZnO. This dependence could potentially be exploited for device application purposes.

Hydrogen Concentration Analysis in Pecvd and Rtcvd Silicon Nitride Thin Films and It's Impact on Device Performance

2001 ◽  
Vol 664 ◽  
Author(s):  
C. Y. Wang ◽  
E. H. Lim ◽  
H. Liu ◽  
J. L. Sudijono ◽  
T. C. Ang ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Threshold Voltage ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Gate Oxide ◽  
Nitride Film ◽  
Device Performance ◽  
Gas Flow Ratio ◽  
The Impact

ABSTRACTIn this paper the impact of the ESL (Etch Stop layer) nitride on the device performance especially the threshold voltage (Vt) has been studied. From SIMS analysis, it is found that different nitride gives different H concentration, [H] in the Gate oxide area, the higher [H] in the nitride film, the higher H in the Gate Oxide area and the lower the threshold voltage. It is also found that using TiSi instead of CoSi can help to stop the H from diffusing into Gate Oxide/channel area, resulting in a smaller threshold voltage drift for the device employed TiSi. Study to control the [H] in the nitride film is also carried out. In this paper, RBS, HFS and FTIR are used to analyze the composition changes of the SiN films prepared using Plasma enhanced Chemical Vapor deposition (PECVD), Rapid Thermal Chemical Vapor Deposition (RTCVD) with different process parameters. Gas flow ratio, RF power and temperature are found to be the key factors that affect the composition and the H concentration in the film. It is found that the nearer the SiN composition to stoichiometric Si3N4, the lower the [H] in SiN film because there is no excess silicon or nitrogen to be bonded with H. However the lowest [H] in the SiN film is limited by temperature. The higher the process temperature the lower the [H] can be obtained in the SiN film and the nearer the composition to stoichiometric Si3N4.

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