Ar+'s impact on Cu(001) : a combined study of moleculair dynamics and kinetic Monte-Carlo simulations and scanning tunneling : microscopy experiments of sputtering processes on Cu(001)

Bollmann, T. (2006) Ar+'s impact on Cu(001) : a combined study of moleculair dynamics and kinetic Monte-Carlo simulations and scanning tunneling : microscopy experiments of sputtering processes on Cu(001).

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Abstract:To be able to simulate the evolution of the surface morphology of Cu(001) after Ar-ion bombardment we perform Molecular Dynamics and experiments to model a single ion impact. In this thesis we used Moleculair Dynamics simulations to find the sputtering-, adatom-, interstitials- and surface- and bulk vacancies after the impact of an Ar-ion on the Cu(001) surface. Combining this with a random impact position we found a sputtering yield of about 3-4 atoms for temperatures up to 150K, for higher temperatures the sputtering yield increases. The adatom yield is found to be 2-8 atoms and the vacancy yield is found to be 4-8 monovacancies. In our simulations we hardly find evidence for the creation of bulk vacancies on impact. Interstitials are created but almost immediatly anneal to the surface. In order to analyse single ion impacts using the Scanning Tunneling Microscope we perform experiments using a low ion dose and low temperature. For low fluence we find that one single Ar-ion impact on Cu(001) creates on average one vacancy cluster of about 6-7 monovacancies and 1-2 adatom cluster of about 7 atoms each. We determined the sputtering yield from experiments at high temperatures and higher ion doses. These experiments result in a sputtering yield of about 0.2 atoms per ion. Using a Kinetic Monte-Carlo algorithm we are able to calculate the evolution of the surface morphology using very simple models for the Ar-ion impact on Cu(001). We compare qualitatively the results with those obtained from performed experiments
Item Type:Essay (Master)
Clients:
VSF Group
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Applied Physics MSc (60436)
Link to this item:http://purl.utwente.nl/essays/58980
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