High <i>K</i> Nanophase Zinc Oxide on Biomimetic Silicon Nanotip Array as Supercapacitors

Abstract

A 3D trenched-structure metal–insulator–metal (MIM) nanocapacitor array with an ultrahigh equivalent planar capacitance (EPC) of ∼300 μF cm^–2 is demonstrated. Zinc oxide (ZnO) and aluminum oxide (Al₂O₃) bilayer dielectric is deposited on 1 μm high biomimetic silicon nanotip (SiNT) substrate using the atomic layer deposition method. The large EPC is achieved by utilizing the large surface area of the densely packed SiNT (∼5 × 10¹⁰ cm^–2) coated conformally with an ultrahigh dielectric constant of ZnO. The EPC value is 30 times higher than those previously reported in metal–insulator–metal or metal–insulator–semiconductor nanocapacitors using similar porosity dimensions of the support materials