Investigation of the effect of helium ion (He+) irradiation on the fluorescence properties of microdiamonds grown by chemical vapour deposition

In this study, we explore the effects of bulk defects introduced using high energy helium ion (He ⁺ ) irradiation on the fluorescence properties of microdiamonds grown using the chemical vapour deposition (CVD) method. 2 MeV He + ions at varying fluences were employed to create lattice defects at several micrometre depth with respect to the crystal surface. Lattice damage was estimated using the Stopping and Range of Ions in Matter (SRIM) software package. When combined with confocal fluorescence microscopy, the results show that the fluorescence primarily arises from the silicon-vacancy (Si-V) ⁻ colourcentres as well as the nitrogen-vacancy (N-V) Frenkel pairs. After irradiation with He + ions, the fluorescence output increased significantly (by around 8 times), suggesting that the proposed irradiation treatment increases the number density of fluorescent defects in diamonds.