Preparation And Properties Of Co-doped ZnO Films

Transparent conductive oxide thin film have been extensively studied in recent years due to their optical and electrical properties.Some of them are good candidates for transparent conductive oxide films.Among them,ZnO is one of the metal oxide semiconductors suitable for use in optoelectric devices.ZnO is aⅡ-Ⅵgroup wide band-gap compound semmiconductor.At room temperature,in has a wide band-gap of 3.37 eV,low power threshold for optical pumping at room temperature and UV emission resulting from a large exciton binding energy of 60 meV.ZnO is high chemical and thermal stability and abundance,it could be an attractive material for a wide variety of applications.Though indium tin oxide films (ITO films) have been widely used,transparet ZnO films are also under investigations by many researchers because it can be attained fairly low resistivity at a low substrate temperature,and compared with the ITO films,the ZnO films has many advantage of abundance in natural resources,easy productions procedure,low cost,non-toxic,high thermal stability and chemical stability.Transparent conducting Al-Zr co-doped ZnO thin film were successfully prepared on slide substrates by DC magnetron sputtering, at room temperature.XRD and SEM were used to analysis and observation the structure and surface morphology of the film.The structural and photoelectrical properties of the films were studied for different sputtering power,sputtering pressure,sputtering time, the distance between target and substrate in detail.The experimental results show that all the films are polycrystalline with a hexagonal structure and a preferred orientation along the C-axis.The lowest resistivity was 1.05×10-3Ω·cm and the average transmittance in visible range was over 93% when optimal preparation parameters.Zr-Ga co-doped ZnO transparent conductive films were deposited on glass substrate using DC magnetron sputtering at room temperature.The influence of sputtering parameters on the structural,electrical and optical properties of Zr-Ga co-doped ZnO films was investgated by XRD,SEM,digital four-point probe and optical transmission spectroscopy.The lowest resistivity of the Zr-Ga co-doped ZnO films is 1.98×10-4Ω. cm and the average transmittance of the films is over 90% in the visible range.The obtained optical band gap of these films is much larger than of pure ZnO (3.34 eV).