Cu2O porous nanostructured films fabricated by positive bias sputtering deposition

TL;DR

This paper reports a novel positive bias sputtering method to fabricate Cu2O porous nanostructured films with controllable morphology and optical properties, introducing a new tip charging model to explain the formation mechanism.

Contribution

It introduces a new positive bias deposition approach in magnetron sputtering to control Cu2O nanostructure formation, supported by a proposed tip charging model.

Findings

Porous Cu2O films with triangular pyramids-like structures were achieved.

The films showed a preferred (111) orientation and a band gap of 2.35 eV.

Traditional bombardment effects were negligible during deposition.

Abstract

In this work, the authors fabricated Cu2O porous nanostructured films (PNFs) on glass slide substrates by the newly developed positive bias deposition approach in a balanced magnetron sputtering (MS) system. It was found that the surface morphology, crystal structure and optical property of the as-deposited products were greatly dependent on the applied positive substrate bias. In particular, when the substrate was biased at +50 V and +150 V, both of the as-prepared Cu2O PNFs exhibited a unique triangular pyramids-like structure with obvious edges and corners and little gluing, a preferred orientation of (111) and a blue shift of energy band gap at 2.35 eV. Quantitative calculation results indicated that the traditional bombardment effects of electrons and sputtering argon ions were both negligible during the bias deposition in the balanced MS system. Instead, a new model of tip charging effect was further proposed to account for the controllable formation of PNFs by the balanced bias sputtering deposition.