Influence of gas chemistry on Si-V color centers in diamond films

Abstract

In this paper, we studied the influence of process parameters on the incorporation and optical activity of the silicon vacancy (Si-V) zero phonon line (ZPL) in diamond films. The ZPL intensity at 738 nm is studied in nano- and micro-crystalline diamond films deposited by microwave plasma enhanced CVD as a function of a substrate temperature, gas composition, i.e. CO2 and N2 concentrations in the gas mixture. We found that the ZPL intensity of Si-V center is independent in a broad deposition temperature range from 450 °C to 1100 °C with a full width of half maxima (FWHM) of 6 nm. For the lowest deposition temperature (350 °C), the ZPL intensity decreases and the FWHM doubles. The Si-V center ZPL vanished for admixtures of 1% CO2 or 2.5% of N2 and higher in the gas mixture. For smaller concentrations, the ZPL intensity gradually decreased while keeping the ZPL peak position and FWHM constant. The influence of CO2 and N2 addition on the diamond morphology is also discussed with respect to the presence of Si-V centers.