Structure, radiation damage and annealing effects in diamond implanted with a high fluence of a few MeV carbons

Crystallinity of the type-Ib single crystal diamond damaged with 3 MeV carbon ions to a fluence of 2 × 1016 cm−2 and subsequent post-implantation anneal at 1200 °C in a hydrogen plasma atmosphere was investigated. The annealed sample had very low optical transmission, suggesting occurrence of graphitization due to an excess introduction of radiation defects and the following post-implantation annealing. In this optical transmission spectrum, an interference pattern was also observed. Combination of such an interference pattern with a TRIM simulation demonstrated that a thin highly defective layer was formed around the depth of ∼1.6 μm, whereas the optical transparent diamond is preserved as an over-layer in the depth region from the surface to ∼1.6 μm. In the photoluminescence (PL) spectra of such a residual thin diamond over-layer, a very broad luminescent band appeared in the spectral range 1.4–2.3 eV. The data of time-resolved PL measurements allowed one to resolve this broadband to two types of bands peaking at ∼1.6 eV and ∼1.9 eV. The ∼1.6 eV band is probably the "B-band" originated from the radiation defects introduced by the ion-implantation. It seems that the ∼1.9 eV band consists of phonon sidebands of zero phonon lines (around 2.1–2.3 eV) of two types of optical centers, but the further studies are required for detailed identifications of these optical centers