Macroscopic high density nanodisc arrays of zinc oxide fabricated by block copolymer self-assembly assisted nanoimprint lithography

Abstract

We report a facile means of creating nanodisc arrays of ZnO with high densities (∼22 Gbit in−2) and narrow distributions in size, shape and periodicities (<15%) using a combination of block copolymer self-assembly and nanoimprint lithography (NIL). ZnO nanodisc arrays with sub-100 nm spatial resolutions, using high-throughput and manufacturing compatible approaches are realized. The fabrication combines benefits from the use of NIL, which is a high-throughput and repeatable tool and from the use of block copolymer self-assembly which provides for low-cost production of high-resolution NIL molds. Preliminary results of the investigation of memory performance of these arrays within MOS capacitor devices show a flat-band voltage shift of 2.53 V at a relatively low operating voltage of 10 V. A high charge trap density of 2.3 × 1018 cm−3 combined with excellent retention of ∼80% after 1000 s of discharging is observed with low tunnelling oxide thickness of 3 nm, demonstrate significant promise of the ZnO nanodiscs to act as charge storage centers in non-volatile flash memory devices.