An STM study of the development of surface features on gold under low-energy helium ion bombardment

The development of small-scale surface topography on initially atomically flat gold surfaces under irradiation with 3 keV helium ions has been investigated using a scanning tunneling microscope (STM). The study has revealed surface features that appear to result from the underlying defect morphology in the implanted metal rather than from sputter-erosion processes occurring at the surface. These features are stable at room temperature. Smaller, sub-monolayer height “bumps” have also been observed under some conditions. It is postulated that these features may be an electronic rather than an elastic effect.