Scanning probe microscopy and computer simulations: Complementary techniques for nanostructured materials and thin films

摘要

It is demonstrated how scanning force microscopy in combination with recent simulation techniques and computer power can be used in a complementary way in the analysis and explanation of thin film growth and nanoindentation on crystal surfaces. Simulation techniques such as Monte Carlo models and molecular dynamic models are applied for thin film growth and nanoindentation. The formation of the first molecular layers in the growth of C-60 films on silicon can be modelled by classical molecular dynamics to show the different bonding behaviour between C-60 molecules, which results in hexagonal and cubic structures with stacking faults within the C-60 film. Ab initio calculations of C-60 bonding sites to the silicon surface classify bond types by the length and the energy of the C-Si bonds. Strong binding energies between the C-60 molecule and the Si atoms are obtained to fix the C-60 molecule at a definite position. Different growth modes such as island and layer growth of C-60 films can be studied by Monte Carlo simulations, including diffusion of atoms within the cluster and cluster diffusion over the surface itself A brief experimental view of the nanoindentation process is given in combination with molecular dynamics simulations for the penetration of the tip into a C-60 surface. The crystal symmetry is reflected during the plastic deformation in the pile-up structure around the indentation hole in relation to the orientation of the indenter and the crystal surface. As an example of these investigations results are given for nanoindentation into the Fe{110} single crystal surface. [References: 36]