The influence of copper on zinc oxide properties – a review

Abstract

ZnO has been experiencing a research renaissance for several years due to its promising electronics and gas sensing properties. It has a relatively big Eg = 3.37 eV at room temperature, a considerable exciton binding energy (60 meV), and exhibits n-type conductivity.One of the most significant advantages of ZnO is its ability to fine-tuning the conductivity and forbidden energy with doping.Doping with transition metals can enhance zinc oxide’s physical, chemical, and optical properties. One such material is copper, which seems to be an interesting dopant due to its high electric conductivity and similar ionic radii. The possibility of achieving the half-metallic ferromagnetism, p-type conductivity, or shifting the luminescence edge to the blue region seems tobe an exciting feature for modern electronics. What is more, Cu doping may increase the thermal resistivity, which can be applied as the material in high-power devices.The following article consists of a detailed review of studies of copper doped ZnO. The first part of the paper consists of a deep look into the properties of ZnO and the purpose of copper doping of ZnO structures. Due to a wide variety of synthesis methods, the second part consists of studies on the production methods of such structures. The central part of an article is correlated with the studies on structural and optical characterization of Cu doped ZnO; thus, the main body of this paper is divided into three sections.For crystal structure, we derive the analysis of XRD patterns, which gives information on the sub-phases, which may form due to doping. In addition, UV-Vis absorption gives insight into the new material’s band structure. Finally, a short section about photoluminescence brings attention to potential applications in LED diodes.