Mn-doped Zinc Oxide Thin Film Preparation And Optical Properties

In recent years,Diluted Magnetic Semiconductors-DMS based ZnO has become a hotspot in the research field of material.ZnMnO is one of them.In this paper,the ZnMnO thin films have been prepared by direct current magnetron sputtering on glasses studied by combining theory and experiment studies.The structural and optical properties of ZnMnO thin films have been systemically investigated.The influences of preparation technology on the characteristic of ZnMnO thin films have also been studied.The structure and surface morphologies of ZnMnO and ZnO thin films are analyzed.XRD pattern indicates that the(002)peak position of ZnMnO film shift to lower angle comparable with that of bulk ZnO owing to Mn²⁺replacing Zn²⁺.A ZnMnO film is single crystals with the hexagonal crystal structure and has a strongly preferred orientation of c axis.X-ray photoelectron spectroscopy(XPS)results reveal the divalent Mn²⁺ions have doped into ZnO lattice,including some small amount of MnO₂.Atomic Force Microscope shows that doping with Mn ion can improve the surface morphologies of films.The optical properties of ZnO and ZnMnO films are discussed.The both have a sharp absorption edge in the UV region.By calculating the bandgap energy of ZnMnO is 3.219 eV which is bigger than that of ZnO. A fast estimation of films is proposed.UV(391.8 nm),blue(463.6 nm) and green(498.9 nm)peaks are observed in photoluminescence(PL) spectra.The UV emission may correspond to Zn-Mn oxide,the blue emission may correspond to the dot defects,the green emission may correspond to the electron transition from the bottom of the conduction band to the acceptor level composed of zinc defects.The influence of deposition condition,such as,substrate temperature, sputtering power and working pressure,on the surface morphologies, transmission,bandgap and photoluminescence of ZnMnO thin films have been studied.As shown by the experiment result,the preferred reaction conditions are presented as follows:substrate temperature-200℃; sputtering power-100 W and working pressure-5 Pa.The effect of oxygen partial pressure on ZnMnO thin films was mainly investigated.The results show that the bandgap and the crystal grain size is maximum with a preferred orientation,when oxygen partial pressure is 0.4.