Surface smoothing of single-crystal diamond (100) substrate by polishing technique

In this study, we investigated the possibility of removing and smoothing a single-crystal diamond (100) substrate by our proposed polishing method utilizing hydroxyl radicals (OH radicals) generated on an Fe surface in hydrogen peroxide solution. To demonstrate the feasibility of removing a diamond surface, an Fe rod and a diamond substrate were rubbed together in hydrogen peroxide solution, then the area on the diamond surface that had come into contact with the Fe rod was observed in detail. Moreover, we attempted to planarize the diamond surface by our proposed method. The surface roughness was measured and evaluated by phase-shift interferometric microscopy and atomic force microscopy. The results show that the surface roughness on a diamond substrate is markedly improved from 2.24nm Ra to 0.16nm Ra after 10h polishing. These results offer useful information for the precise smoothing of single-crystal diamond substrates. ► We proposed a precision polishing method for single-crstal diamond substrates. ► Our proposed method utilizes hydroxyl radicals generated on an Fe surface in hydrogen peroxide solution. ► We observed the surface morphological change due to polishing. ► The resultant diamond surface has atomic-level smoothness.