Formation of low-dimensional nanopit structures on atomically flat surfaces of diamond (111) by nickel nanoparticles

Diamond nanoprocessing technologies are essential for the development of diamond-based devices. However, the existing etching processes damage the diamond crystal, adversely affecting the characteristics of the corresponding device. Herein, we focused on the Ni–C solid-solution reaction as a nondamaging fabrication method. Ni films (10, 3, and 1 nm) were deposited on atomically flat surfaces (AFSs) of diamond (1 1 1) and annealed under H2 gas flow. The Ni film aggregated into particles, and as the particle size decreased, Ni particles moved around, etching the diamond surface. Interestingly, when the diameter of the Ni nanoparticles was less than a few tens of nanometers, they dug one-dimensional (1D) nanopits with a linear trench shape on diamond AFS. We discuss the mechanism for the formation of these 1D nanopits in detail from the perspective of the etching-morphology dependence on the annealing time, Ni thickness, and gas atmosphere. The results of this study will improve our understanding of the Ni–C solid-solution reaction at the nanoscale and promote the development of damage-free nanofabrication techniques for diamond-based device applications.