Enhanced nanoparticle formation by indentation and annealing on 2 MeV Cu ion-implanted SiO2

Enhancement of surface plasmon resonance (SPR) in optical absorption has been found on Cu ion-implanted SiO2 substrate modified by micro-indentation and post-annealing. Micro-indentation effects on surface plasmon resonance (SPR) in optical absorption have been studied to control nanoparticle formation in Cu ion-implanted SiO2 substrate. The SiO2 was firstly implanted with 2 MeV Cu2+ ions at an ion flux of 4 μA/cm2, up to a fluence of 6 × 1016 ions/cm2. After the ion implantation, dot-array patterns of micro-indents were made by a micro-Vickers hardness tester, and followed by annealing at 600 °C in vacuum for 1 h. The optical absorption spectra of the indented region and the non-indented flat region were measured and compared with each other. After post-annealing at 600 °C, the indented area showed higher absorbance of SPR at 2.2 eV than that of the flat region annealed under the same annealing conditions. The TEM study shows larger and denser Cu precipitates inside the indentation than those in the flat area. The results indicate that the defects produced by indentation enhance the atomic migration in the plastic zone during thermal relaxation process, resulting in promoting the enhanced precipitation of Cu nanoparticles.