Animations of bulk collision cascade development

K. Nordlundš˛ and R. S. Averbackš

š Materials Research Laboratory, University of Illinois at Urbana-Champaign Urbana, IL 61801, USA

˛ Accelerator Laboratory, University of Helsinki, P.O. BOX 43, FIN-00014 Helsinki, Finland

(October 10, 1997)

The development of collision cascades in bulk solids varies strongly with the atomic mass, density and crystal structure. This page illustrates the development of collision cascades in Si, Ge, Al and Au with animations of the collision cascades.

This material is auxiliary material to the publication "Defect production in collision cascades in elemental semiconductors and FCC metals", by K. Nordlund, M. Ghaly, R. S. Averback, T. Díaz de la Rubia, M. Caturla and J. Tarus (Phys. Rev. B 80 (1998) 4201). A preliminary preprint is available here. Related publications can be found in my publication database.

Snapshots and animations of cascade development

To obtain an animation of the cascades in any of the materials, click on either the 2D or 3D buttons to obtain a 2-dimensional or 3-dimensional view. Each dot shown is an energetic atom; the colors are proportional to the depth scale in the 2D figures, and proportional to the energy in the 3D ones, with the red atoms being hottest at the given time. In the 3D figures, also the atoms size is proportional to the kinetic energy. (To view the animations, you need a web browser or browser plugin which can show GIF animations. Recent versions of Netscape or Microsoft Internet Explorer should be able to do this).

10 keV Si 2D 3D	10 keV Al 2D 3D
10 keV Ge 2D 3D	10 keV Au 2D 3D
10 keV Cu 2D 3D	50 keV Ni 3D

We illustrate the development of the collision cascades using figures and animations which show all "liquid" or "hot" atoms during the development of the collision cascade. An atom was interpreted to be liquid if the average kinetic energy of it and its neighbours was above the melting point of the material.

For a scientific discussion of the cascade development illustrated here, please refer to the publication mentioned above.

The snapshots on this page (above, and below in greater detail) show liquid atoms produced by 10 keV cascades in silicon, germanium aluminum, copper and gold at times when the number of atoms in large continuous liquid regions was at a maximum. The atom sizes and colors illustrate the kinetic energy of each atom, with the hottest atoms being larger and yellow or red. The bounding boxes show the total size of the simulation cells, which have been rotated to provide a clear view of the nature of the damage.

By clicking on the figure you will obtain a gif animation of the time development of a similar cascade In the 2D animations, each dot shows the position of one atom at the given time. The colors show the depth (z scale) according to the legend to the left in the 2D animations, and the energy on a relative scale scale in the 3D figures. The time scale is running on the top left corner of the figure. After the animation finishes, it will restart from the beginning.

In the gold cascade shown here, two replacement collision sequences emanate out from the center of the cascade, producing a trail of hot atoms in their wake. Note that this long replacement collision are quite rare, seen only in a few events. Mostly 10 keV cascades in heavy metals form almost spherical cascades like the one shown for Cu above.