Preparation And Characterization Of ZnO-based Multilayer Transparent Conductive Films Based On D/M/D Structure

The transparent conductive oxide film (TCO) has a low resistivity and hightransmittance in the visible range. Nowdays it has been widely used in a liquid crystaldisplay (LCD), organic light emitting diode (OLED), solar battery and other fields.Indium tin oxide (ITO) thin film has been considered as ideal material for transparentconductive film, but nature reserves of Indium is very low and Indium also has strongtoxicity, so that the cost of preparing ITO film is huge. In recent years, the wide bandgap semiconductor ZnO materials become really hot in optoelectronic field.Especially, Al-doped transparent conductive film (AZO) and Ga-doped transparentconductive film (GZO) will gradually replace ITO films. However the crystal qualityis poor when preparing AZO and GZO films by magnetron sputtering. The greatinfluence of the substrate temperature and the annealing conditions are hard to dealwith, so it is difficult to satisfy the requirements of quality transparent conductive thinfilm.In this paper, ZnO/Ag/ZnO, ZnO/Au/ZnO multilayer films are our researchtarget. Without introducing doping source, ZnO films are manufactured by MetalOrganic Chemical Vapor Deposition (MOCVD). The metal interlayer is produced byradio frequency magnetron sputtering and annealed by light annealing furnace. Thestructural, electrical and optical properties of multilayer films are investigated byatomic force microscope (AFM), scanning electron microscopy (SEM), X-raydiffraction instrument (XRD), hall effect measurement and transmission spectraanalysis. The multilayer films are combined with p-Si/n-ZnO hetero-junction lightemitting devices in the end.The study is divided into three stages:（1）Preparation of high-quality ZnO thin films.By using MOCVD film epitaxial technology, ZnO thin films were prepared on glass and sapphire substrates. The thickness influence on the structure, electrical and opticalproperties are studied.（2）Preparation of the metal thin filmsThe metal films are prepared by RF magnetron sputtering. the film thickness isdecided by controlling the growth parameters. The mental films are annealed by lightannealing furnace. The impact of different thickness and annealing temperature on themetal Ag films and t Au films’ structure and optical properties are investigated.（3）Preparation of ZnO-mental-ZnO multilayersBased on comprehensive study of the first two steps, the growth parameters ofZnO-mental-ZnO multilayer are optimized. The impact of mental layer thickness andannealing temperature on structural, optical and structural properties of the multilayerfilms is studied.Experimental results show that the good electrical conductivity and lighttransmittance can be achieved only when the thickness is less than15nm. In thevisible region, the transmittance falls sharply when the thickness of mental films areincreasing. However, if the thickness is too much small, the electrical conductivitywill be damaged. Meanwhile the appropriate heat treatment could enhance theoptoelectronic and structural properties of the films.