Fabrication of diamond nanocones and nanowhiskers by bias-assisted plasma etching

Nanodiamond film surfaces were structured into high-aspect-ratio nanodiamond cones and whiskers by utilizing bias-assisted reactive ion etching (RIE) in hydrogen/argon microwave plasmas. The role of Ar addition in the RIE process was investigated by varying the argon concentration in a wide range from 5 to 75% in the plasma. Based on the dependence of the density and the geometrical configuration of cones/whiskers on RIE conditions, the formation mechanism of these nanodiamond structures was discussed. It was found that the formation of the conical/whisker structures was correlated with the original column structure of nanodiamond films. The bias-assisted RIE structuring involves both physical and chemical etching, and the addition of Ar in the plasma is capable of enhancing the physical etching significantly.