Molecular dynamics study of tilt grain boundary evolution during the growth of beryllium thin films

Beryllium films fabricated by magnetron sputtering deposition unavoidably contain grain boundaries (GBs), which have a substantial effect on the resulting material properties. The growth dynamics and evolution of various tilt GBs were explored using a direct molecular dynamics vapor deposition simulation. The effects of the incident energy, incident angle and substrate temperature on the film morphologies were also considered. The results show that GBs and dislocations were extended to the epitaxial layer during the growth of the beryllium thin films. The types of GBs were maintained and were closely related to the surface topography of the substrate. An increased incident energy and substrate temperature enabled the formation of good-quality beryllium films. However, large incident angles resulted in the formation of defect structures in the interior of the beryllium films. The low-angle GBs were more stable than the high-angle GBs. Large incident energies (above 10 eV) with large incident angles (above 38 degrees) always accompanied increased numbers of reflected atoms. In brief, during the growth of the beryllium thin films, the GBs were extended to the epitaxial layer, and the types of GBs were maintained. In addition, incident energies about 5 eV with incident angles less than 30 degrees are desired to form improved Be films.