Precise tailoring of evaporated gold nanocones using electron beam lithography and lift-off.

The ability to fabricate nanocones with precise dimensions is essential for several emerging applications. We demonstrate here a method which can be used to fabricate arrays of gold nanocones with high dimensional precision using lithographic and lift-off means. electron beam (ebeam) writing of a spin-coated PMMA-based bilayer resist deposited onto silicon wafers is used to form a shadow mask. This mask gradually closes as the deposition of gold (using ebeam evaporation) proceeds-the result is arrays of gold nanocones on the silicon wafer surface after lift-off of the resist. Observations using scanning electron microscopy enable a statistical study of the dimensions of 360 gold nanocones-the results demonstrate the high precision of the nanocones dimensions. The fabrication process enables the creation of arrays of nanocones with a base diameter varying from 53.6 2.1 nm to 94.1 2.4 nm, a vertical height ranging from 71.3 4.1 nm to 153.4 3.4 nm, and an apex radius of curvature ranging from 8.4 1.2 nm to 11.6 1.5 nm. The results are compared with the predictions of a deposition model which considers the evolving shadow masking during the gold deposition to compute the nanocone profile.