Estudos de dinamica molecular aplicados ao crescimento epitaxial e nanoindexação / Studie pf molecular dynamics applied to the epitaxial growth and nanoindentation

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

In this work we present two important and current subjects:Metalic thin .lms and nanoindentation. We studied these systems using molecular dynamics with empirical potentials. We showed that it is possible to model the epitaxial growth using a suitable potential and a specific methodology for deposition.Concerning the growth of thin films,we studied three systems using EAM potential:Cu/Ag(001),Cu/Au(001)and Pd/Au(001).For Cu on Au and Cu on Ag,our results are in agreement with previous experiments. We stress that the existence of a bcc and bcc/bct are related to temperature and thickness of the deposited film. We showed that during the deposition of the first few layers,the film grows under stress to form an unstable bcc phase,but after a critical thickness it relaxes in a bct structure.Then,when the film is relaxed it presentes a deformation pattern (stripes). The relationships between temperature,thickness and formed structures are presented. For the case of Pd on Au the growth resulted in a deformation pattern after we deposited 11 mono-layers. We analysed the structures and found defect types known as stacking faults. To model semiconductors systems we used the Tersoff potential. We indented a surface of silicon with a spheric indenter of diamond.A graph of dislocation as function of pressure for the indenter is presented. We analysed the coordination number of silicon atoms when the indenter reached specific values of pressure

ASSUNTO(S)

filmes finos nanoindentação nanoindentation thin films crescimento epitaxial epitaxial growth

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