High k nanophase zinc oxide on biomimetic silicon nanotip array as supercapacitors.

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 × 10(10) 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.