Progress in Surface Engineering Using Slow Highly Charged Ions

The irradiation with highly energetic (MeV-GeV) heavy ions can produce modifications to the properties of different materials. Among the observed effects, fabrication of nanostructures in different materials surfaces was demonstrated. Recently, slow (eV-keV) highly charged ions (HCIs) were successfully utilized for the fabrication of similar surface nanostructures in various solids. However, HCI exhibits unique features by altering only the upper most surface layers without modifying the deeper layers, which cannot be avoided for MeV-GeV heavy ions. Based on both the material properties and ion parameters (charge state, kinetic energy, potential energy, etc.), surface structures of various geometries (hillocks, caldera-like, pits) and sizes were obtained. This paper reviews the research progress of surface engineering by HCI and the available theoretical models for understanding the creation mechanisms of the formed nanostructures.