Effects of focused electron beam irradiation parameters on direct nanostructure formation on Ag surfaces

Abstract

Metallic nanostructures have many applications, including photonics and plasmonics due to their ability to absorb or emit light at frequencies which depend on their size and shape. It was recently shown that irradiation by a focused electron beam can promote nanostructure growth on metal surfaces and the height of these structures depends on irradiation time and material of the surface. However, the effects on growth dynamics of numerous irradiation parameters, such as beam current or angle of incidence, have not yet been studied in detail. In this work, we explore the effects of the focusing, the angle of incidence, and the current of the electron beam on the size and shape of the resulting structures on an Ag surface, as well as investigating how the nitrogen plasma cleaning procedure of a vacuum chamber can affect the growth of these structures. A beam current of around 40 pA resulted in the fastest structure growth rate. Increasing the beam diameter and angle of incidence decreased the growth rate, but raising the beam focus up to 5-6 μm above the surface increased it. The vacuum chamber cleaning reduced the structure’s growth rate for a few hours. These findings can help better control and optimise the nanostructure growth on metal surfaces undergoing irradiation by a focused electron beam.