Realization of an atomically flat surface of diamond using dressed photon-phonon etching

We obtained an atomically flat diamond surface following dressed photon-phonon (DPP) etching using 3.81eV light and O ₂ gas. We obtained a surface roughness (R _a) of 0.154nm for Ib-type (111) diamond and 0.096nm for Ib-type (100) diamond. To evaluate the surface roughness, we grouped the surface into bins of width l and introduced the standard deviation of the height difference function for a given separation l, which allowed us to determine the height variation of the surface. Based on the calculation of standard deviation, the conventional adiabatic photochemical reaction did not remove the small surface features, while DPP etching decreased the surface roughness for all length scales.