Electron Irradiation Effects in Au thin Flms

Room temperature 200 keV electron irradiation effects on the area retraction behavior presented by 6.75 nm thick Au thin films deposited over a self-standing SiO 2 / silicon nitride membrane are investigated as a function of the irradiation fluence Φ. The as-deposited films already contain void discontinuities. The void growth behavior is investigated considering irradiation and thermally-induced surface atoms’ migration. The film’s coverage area A(Φ) and void perimeter P(Φ), obtained via Transmission Electron Microscopy observations, allow for calculating the atomic displacement causing the area retraction. This data is compared with model calculations of irradiation and thermally-induced atomic fluxes. The results demonstrate that the balance between the thermal and irradiation processes strongly depends on the choice of the surface thermal diffusivity values, which present large discrepancies in the literature. Our results suggest that irradiation-induced atomic displacements follow the same thermodynamic driving forces acting in thermal processes. The work also discloses a new method to investigate surface atoms’ behavior and promote microstructural modifications at room or lower temperatures.