Fabrication of thin diamond membranes by Ne implantation

Color centers in diamond are one of the most promising tools for quantum information science. Of particular interest is the use of single-crystal diamond membranes with nanoscale-thickness as hosts for color centers. Indeed, such structures guarantee a better integration with a variety of other quantum materials or devices, which can aid the development of diamond-based quantum technologies, from nanophotonics to quantum sensing. A common approach for membrane production is what is known as"smart-cut", a process where membranes are exfoliated from a diamond substrate after the creation of a thin sub-surface amorphous carbon layer by He$^+$ implantation. Due to the high ion fluence required, this process can be time-consuming. In this work, we demonstrated the production of thin diamond membranes by neon implantation of diamond substrates. With the target of obtaining membranes of $\sim$ 200 nm thickness and finding the critical damage threshold, we implanted different diamonds with 300 keV Ne$^+$ ions at different fluences. We characterized the structural properties of the implanted diamonds and the resulting membranes through SEM, Raman spectroscopy, and photoluminescence spectroscopy. We also found that a SRIM model based on a two-layer diamond/sp$^2$-carbon target better describes ion implantation, allowing us to estimate the diamond critical damage threshold for Ne$^+$ implantation. Compared to He$^+$ smart-cut, the use of a heavier ion like Ne$^+$ results in a ten-fold decrease in the ion fluence required to obtain diamond membranes and allows to obtain shallower smart-cuts, i.e. thinner membranes, at the same ion energy.