Surface modification for brittle monocrystalline materials by MeV ions

Abstract

A novel method of MeV ion implantation surface modification for improving the mechanical properties of brittle monocrystalline materials is proposed. The mechanical properties of the surface layer of the material are modified in a depth up to a few micrometers by decrystallization using low influences and high energy ion bombardments. Implantations are carried out on monocrystalline silicon using a van de Graaff accelerator with 10 MeV F ion and a fluence of 1 × 10 14 ions cm −2. Focused Ion Beam (FIB) equipped with an in situ rotational nanomotor is used to make cross-sectional Transmission Electron Microscopy (TEM) samples for the modified layer. Large penetration depth nano-indentation is carried out and surface topography after indentation is observed by Scanning Electron Microscopy (SEM). TEM and electron diffraction analysis show the existence of the amorphous phase, nano-indentation results reveal the reduction of the brittleness, hardness and elastic modulus of the implanted surface. Therefore, the method is beneficial for the nano-manufacturing process for enhancing the plasticity of the brittle monocrystalline materials and introducing little defects for the low fluences.