Nanostructuring of Iron Surfaces by Low-Energy Helium Ions

The behavior of iron surfaces under helium plasma exposure is investigated as a function of surface temperature, plasma exposure time, and He ion flux. Different surface morphologies are observed for a large process parameter range and discussed in terms of temperature-related surface mechanisms. Surface modification is observed under low-He ion flux (in the range of 10 20 m -2 s -1 ) irradiation, whereas fiberlike iron nanostructures are formed by exposing the surface to a high flux (in the range of 10 23 m -2 s -1 ) of low-energy He ions at surface temperatures of 450-700 °C. The effects of surface temperature and plasma exposure time on nanostructures are studied. The results show that surface processing by high-flux low-energy He ion bombardment provides a size-controlled nanostructuring on iron surfaces.