Study Of The Preparation And Properties Of ZnO:Sn(TZO) Thin Films Prepared By Sol-gel Technique

Transparent conductive oxide thin films are widely used in transparent electrodes, liquid crystal displays, solar cells, anti-static coatings and various electrical and optical devices. It is because of transparent conductive oxide thin films exhibit outstanding optical and electrical properties. At present, transparent conductive oxide thin films include chiefly SnO2,In2O3,ZnO and their dopant systems. Nowadays, indium tin oxide films (ITO) has been widely studied. However, it has some problems such as high cost, toxicity and low stability to hydrogen plasma. So it is necessary to search for new materials. Doped ZnO thin films are a potential candidate for ITO films, which is not only because of their comparable optical and electrical properties to ITO films, but also because of their low price and their higher thermal and chemical stability under the exposure to hydrogen plasma.In this paper, the Sn-doped ZnO (TZO) thin films are deposited on glass substrate by Sol-Gel spin-coating method. Zinc acetate dihydrate (Zn(CH3COO)2.2H2O) is used as a starting material; 2-methoxyethanol and monoethanolamine are used as solvent and stabilizer respectively; the dopant source of tin is tin chloride hexahydrate. The optimum technological parameters for preparing TZO thin films with the best optical and electrical properties are:the sol concentration is 0.5 M, the dopant concentration is 3 at.%, the drying temperature is 300℃, the heat treatment temperature is 500℃, and the cooling condition is-15℃. The resistivity attains 8.2×10-1Ω·cm and the average transmittance attains 85%in the visible range.The structural, morphological, optical and electrical properties of TZO thin films are investigated by X-ray diffraction (XRD),scanning electron microscope (SEM),four-point probe method and UV-VIS spectrophotometer respectively. The results prove that the films are all polycrystalline with a structure of ZnO hexagonal wurtzite type and a preferred orientation of c-axis. The electrical and optical properties of the TZO thin films are influenced by the sol concentration, the dopant concentration and the heat treatment temperature.