Characterisation of Cu2O, Cu4O3, and CuO mixed phase thin films produced by microwave-activated reactive sputtering. (October 2017)

• Record Type: Journal Article
• Authors: Alajlani, Yahya; Placido, Frank; Barlow, Anders; Chu, Hin On; Song, Shigeng; Ur Rahman, Saeed; De Bold, Robert; Gibson, Des
• Is Part Of: Vacuum. Volume 144(2017)
• Page Start: 217
• Page End: 228
• Publication Date: 2017-10
• Subjects: Nanostructure -- Copper oxide -- Microwave-activated reactive sputtering -- OJL model; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2017.08.005
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: Copper readily forms three oxides, CuO, Cu4 O3 and Cu2 O, widely recognised as the most promising p-type oxides because of their desirable optical and electrical properties and potential use in solar cells, transparent electronics as well as other specialised applications such as electrodes for rechargeable lithium batteries, catalysis and memristors. For large-scale implementation of devices, magnetron sputtering is a practical method of producing metal oxides; however, sputtered copper oxides tend to form as a mixture of the oxides, with Cu2 O being particularly difficult to produce reliably in pure form. Here, nanostructured thin films of copper oxides were prepared by a variation on reactive sputtering known as microwave-activated reactive sputtering under various rates of oxygen flow. Microwave-activated reactive sputtering was shown to be a suitable technique for the inexpensive production of large areas of copper oxide thin films at near room temperature, facilitating deposition on a wide variety of substrates including polymers. Furthermore, it was demonstrated that the sputtered films develop through CuO, Cu4O3 and Cu2O mixed phases as oxygen flow rate is increased. The preparation of a given stoichiometry for a particular application can be achieved by varying the flow rate of oxygen during the microwave-activated reactive sputtering process. Highlights: Microwave-activated reactive sputtering found to be inexpensive method to produce copper oxide thin films. Detailed characterisation of the sputtered films is possible with the aid of XPS, XRD, optical and Raman measurements. Controlled deposition of mixtures of various phases of Cu2 O, Cu4 O3, CuO can be determined by oxygen flow rate.