NASCAM (NAnoSCAle Modeling)

Developed by Pavel Moskovkin, Benjamin Bera  and Stéphane Lucas

Description:

This code is developed to simulate the time evolution of atoms deposited on a substrate. It is based on the kinetic Monte Carlo (kMC) method. kMC can be used for modeling different processes at the surface, such as the growth of films during deposition or the development of films post deposit, at the atomic scale.  The goal of the kinetic Monte Carlo method is to mimic real experiments through simulations. Because kMC does not take into account the vibrational movement of atoms it is possible to use kMC to model the evolution of a system for longer periods of time, unlike the Molecular Dynamics simulation which can only be used to simulate the dynamics of a system for a short period of time, about 10-9s. Depending on the number of atoms in the system, along with some other parameters such as temperature and atomic properties, the empirical time (as opposed to simulation) might be hundreds to thousands of seconds.

In the current model, the following events are implemented:

1. free diffusion at the substrate and layer level,
2. hop with same number or increase of neighboring atoms number,
3. hop with decrease of neighboring atoms number,
4. detachment from the island,
5. hop up from one level to another,
6. hop down from one level to another,
7. detrapment from a substrate defect,
8. evaporation from susbtrate or layer
9. sputtering if the transferred energy to an adatom is larger than its surface binding energy.

For each of these events, the user has to specify the activation energy.

One can start a simulation with a pre-existing surface structure like film or island present at the surface before deposition.

Several examples are provided: Diffusion limited aggregation, fractal growth, Otswald ripening,  ...

You can freely download NASCAM (see the link at the botom of this page), but we ask you to register by yourself at the following email address: stephane.lucas@fundp.ac.be. You will then be entitled to any releases and bug corrections.

Two scientific papers on NASCAM applications have been published by the authors:

Simulation at high temperature of atomic deposition, islands coalescence, Ostwald and inverse Ostwald ripening with a general simple kinetic Monte Carlo code, S. Lucas, P. Moskovkin, Thin Solid Films, 518 (2010) 5355-5361.

Surface phenomena involved in the formation of Co nanoparticles on amorphous carbon and SiO2 deposited by magnetron sputtering, S. Lucas, J.F. Colomer, C. Bittencourt, P. Moskovkin, N. Moreau, Appl Phys A(2010) 99:125-138.

We ask you to cite at least the article published in Thin Solids Films in any of your publications involving NASCAM.

Enjoy easy Monte-Carlo !!

Prof. S. Lucas

Past NEWS:

NASCAM v 3.5d3 has been presented at the European Plasma Conference HTPP11 - Bruxelles (www.htpp11.eu/), and released on september 28th 2010.

NASCAM Workshop:

On behalf of BELVAC and the IAP research project “Plasma Surface Interaction (PSI)”, the Research center in Physics of Matter and Radiation (PMR) did organise a two-days workshop on plasma and plasma simulation softwares ( September 1^th and 2^th 2009).

The plasma simulation session was intended to give the opportunity to discover and test three computer programs running on personal computer and able to simulate plasma and/or film growth: Plasimo, Simtra and NASCAM.

Over 40 scientists attended to the lectures and the practices.

Among the proposed work, they had the possibility to discover and evaluate NASCAM through the simulation of several  cases: i- diffusion limited aggregation, ii- deposition on a "flat" substrate at various T° and energies, deposition on a pre-patterned substrate at various T° and energies, simulation of Oswald ripening and inverse Oswatd ripening via the annealing process of pre-defined structres deposited on a surface.

RELEASES

 •Version 2 (2008)