The growth and characterization of diamond cone arrays formed by plasma etching

Diamond cone arrays with high aspect ratio are formed by plasma etching on diamond film grown by hot-filament chemical vapor deposition (HFCVD) method. The cone angle and orientation of etched cones with tip diameter of about 10–20 nm are uniform, and the cone density of cone arrays formed on diamond film can be controlled by changing the etching time during plasma etching. Energy dispersion X-ray analysis (EDX) and Raman spectroscopy show that the cone arrays are composed of carbons in the chemical states of diamond, nanodiamond and amorphous carbons. High-resolution transmission electron microscopy (HRTEM) analysis indicates that diamond cone has an amorphous outer layer and an inner core with certain crystallization. It can be concluded that the outer amorphous layer is formed by the bombardment of carbon containing ions on the diamond surface, and the nanodiamond is formed by the dimensional reduction of original diamond crystalline into nanometer scale. Selected area electrons diffraction (SAED) pattern analysis is used to study the structures of diamond cones. The diamond cone formation is interpreted using the selective etching mechanism of grooves on a rough surface of diamond film.