All-dielectric structural colors are attracting increasing attention due to their great potential for various applications in display devices, imaging security certification, optical data storage, and so on. However, it remains a great challenge to achieve vivid structural colors with low-aspect-ratio silicon nanostructures directly on a silicon substrate, which is highly desirable for future integrated optoelectronic devices. The main obstacle comes from the difficulty in achieving strong Mie resonances by Si nanostructures on low-index-contrast substrates. Here, we demonstrate a generic principle to create vivid bright field structural colors by using silicon nanopillars directly on top of the silicon substrate. Complementary colors across the full visible spectrum are achieved as a result of the enhanced absorption due to Mie resonances. It is shown that the color saturation increases with the increasing of the nanopillar height. Remarkably, blue and black colors are generated by trapezoid nanopillar arrays as a result of the absorption at long wavelengths or all visible wavelengths. Our strategy provides a powerful scheme for accelerating the integrated optoelectronic applications in nanoscale color printing, imaging, and displays.
Keywords: Mie resonances; Si nanostructures; integrated photonics; low-index-contrast substrates; structural colors.