Deterministic fabrication of sharp amorphous silicon oxide nanocones using a single mask

Nanocones with tapered sidewalls exhibit extraordinary and versatile optical properties such as anti-reflection, super-absorption, and supertransmissivity. We present a single-mask dry etching technique for the fabrication of amorphous silicon oxide nanocones featuring sharp tips, smooth sidewalls, and deterministic distribution onto substrates. We demonstrate high aspect ratio nanocones with sidewalls of constant angle and tip diameters limited mainly by the resolution of electron beam lithography. We further introduce a single-mask, multi-step dry etching approach to fabricate ultra-sharp silicon oxide nanocones with tip diameters as small as 10 nanometers by undercutting nanopillars at mid-height, enabling the etching of multi-height nanocones onto a substrate using a single etch. The presented processes introduce exciting possibilities, including the fabrication of transparent dielectric nanocone distributions onto unconventional films and substrates when fused silica and thermally oxidized silicon are unavailable. The presented findings have applications in nanophotonics and strain engineering of two-dimensional materials.