Low-Cost Preparation of Diamond Nanopillar Arrays Based on Polystyrene Spheres

Abstract

Diamond nanopillar arrays can enhance the fluorescence collection of diamond color centers, playing a crucial role in quantum communication and quantum sensing. In this paper, the preparation of diamond nanopillar arrays was realized by the processes of polystyrene (PS) sphere array film preparation, PS sphere etching shrinkage control, tilted magnetron sputtering of copper film, and oxygen plasma etching. Closely aligned PS sphere array films were prepared on the diamond surface by the gas-liquid interfacial method, and the effects of ethanol and dodecamethylacrylic acid solutions on the formation of the array films were discussed. Controllable reduction of PS sphere diameter is realized by the oxygen plasma etching process, and the changes of the PS sphere array film under the influence of etching power, bias power, and etching time are discussed. Copper antietching films were prepared at the top of arrayed PS spheres by the tilted magnetron sputtering method, and the antietching effect of copper films with different thicknesses was explored. Diamond nanopillar arrays were prepared by oxygen plasma etching, and the effects of etching under different process parameters were discussed. The prepared diamond nanopillars were in hexagonal close-rowed arrays with a spacing of 800 nm and an average diameter of 404 nm, and the spacing, diameter, and height could be parametrically regulated. Raman spectroscopy and photoluminescence spectroscopy detection revealed that the prepared diamond nanopillar array still maintains polycrystalline diamond properties, with only a small amount of the graphite phase appearing. Moreover, the prepared diamond nanopillar array can enhance the photoluminescence of diamond color centers by approximately 2 times. The fabrication method of diamond nanopillar array structures described in this article lays the foundation for quantum sensing technology based on diamond nanostructures.

Figure 1

Process flow of diamond nanopillar array preparation (a) growing a diamond film on a silicon substrate, (b) preparing an hexagonal densely arranged PS ball film on the surface of the diamond film, (c) oxygen etching to control the uniform shrinkage of PS balls, (d) tilted magnetron sputtering of the Cu antietch layer, (e) oxygen etching of the diamond film to prepare the nanopillar arrays, and (f) diamond nanopillar arrays obtained after concentrated hydrochloric acid washing.

Figure 2

Preparation of PS ball monolayers under different conditions: (a) PS ball aqueous solution, (b) PS ball/ethanol mixture, and (c) PS ball/ethanol mixture with dropwise addition of SDS solution.

Figure 3

PS ball shrinkage control with different etching parameters. The etching power, bias power, and etching time are (a) 200 W, 50 W, and 1 min, (b) 300 W, 50 W, and 1 min, (c) 400 W, 50 W, and 1 min, (d) 300 W, 0 W, and 1 min, (e) 300 W, 20 W, and 1 min, (f) 300 W, 20 W, and 0.5 min, (g) 300 W, 20 W, and 2 min, (h) 300 W, 20 W, and 3 min, and (i) 300 W, 20 W, and 4 min, respectively.

Figure 4

Etch resistance effect of different thicknesses of copper films: (a) 8, (b) 16, (c) 24, (d) 32, (e) 40, and (f) 48 nm.

Figure 5

Diamond nanopillars with different etching parameters. The etching power, bias power, and etching time are (a) 200 W, 50 W, and 10 min, (b) 300 W, 50 W, and 10 min, (c) 400 W, 50 W, and 10 min, (d) 300 W, 20 W, and 10 min, (e) 300 W, 80 W, and 10 min, (f) 300 W, 50 W, and 5 min, (g) 300 W, 50 W, and 15 min, (h) 300 W, 50 W, and 20 min, and (i) 300 W, 50 W, and 40 min.

Figure 6

Performance testing of diamond nanopillar arrays: (a) AFM detection, (b) Raman spectroscopy, (c) fluorescence scanning, and (d) fluorescence spectroscopy.