General fabrication of ordered nanocone arrays by one-step selective plasma etching

One-step selective direct current (DC) plasma etching technology is employed to fabricate large-area well-aligned nanocone arrays on various functional materials including semiconductor, insulator and metal. The cones have nanoscale apexes (∼2 nm) with high aspect ratios, which were achieved by a selective plasma etching process using only CH₄ and H₂ in a bias-assisted hot filament chemical vapor deposition (HFCVD) system without any masked process. The CH₃ ⁺ ions play a major role to etch the roughened surface into a conical structure under the auxiliary of H⁺ ions. Randomly formed nano-carbon may act as an original mask on the smooth surface to initiate the following selective ions sputtering. Physical impinging of energetic ions onto the concave regions is predominant in comparison with the etching of convex parts on the surface, which is identified as the key mechanism for the formation of conical nanostructures. This one-step maskless plasma etching technology enables the universal formation of uniform nanocone structures on versatile substrates for many promising applications.