Study on Preparation and Opto-electrical Properties of Ga-doped ZnO Transparent Conductive Thin Films
|Course||Materials Physics and Chemistry|
|Keywords||RF magnetron sputtering GZO films Optoelectronic properties Seebeck effect|
Zinc oxide (ZnO) is a Group II-VI direct bandgap (3.3eV) a semiconductor oxide, because of its excellent optical characteristics, in the field of the light emitting device, an ultraviolet detector, a solar cell, a gas-sensitive element, and a surface acoustic wave device obtain a wide range of applications. SnO2: F film now commonly used in transparent conductive films (TCO) ITO, ZnO film has a cheap, high stability in the active hydrogen and hydrogen plasma environment and has become widely accepted. Often used to improve the conductive properties of ZnO, Al, In, Ga, and other element doped, very similar to the ionic radius of Ga and the covalent bond length (0.62? And 1.26?) With Zn (0.74? And 1.34?), High-doped heteroaryl concentration of ZnO lattice distortion is also small, therefore, there is necessary to study the Ga-doped ZnO (GZO) film, in order to obtain a better quality of the TCO film. In this paper, prepared by the RF magnetron sputtering on glass substrates quality GZO transparent conductive film, the substrate temperature, Ga doping concentration, film thickness of the film properties; XRD, AFM, SEM, XPS and UV - visible double beam spectrophotometer testing means the characterization and analysis of the deposited film; study the structure of the film, the electrical, optical, and thermoelectric properties. Through experiments and research, draw the following main results: GZO films prepared wurtzite polycrystalline structure with (002) preferred orientation, and grain size of 10 to 30 nm, and the right amount of Ga doping concentration and lining The temperature at the bottom is possible to improve the crystalline quality, to increase the grain size, so that the surface of the film more dense. XPS analysis showed: Zn and Ga elements respectively to Zn2 and Ga3 form of existence, and not found in other valences of Zn and Ga elements, the thin film of Ga content is slightly higher than the target Ga content. Thickness, doping concentration, and the substrate temperature on the resistivity of the GZO films have a greater impact, increased thickness and moderate doping concentration, medium substrate temperature, which will help to obtain high conductivity performance. Average visible light transmittance of the GZO film were more than 80%, with the doping concentration increased, the optical absorption edge moves towards the short direction, the occurrence of a \Move generated, which is related to the combined effects of the \5. GZO film has a strong pyroelectric effect, the thermal electromotive force is negative, it indicates that the GZO for n-type conductivity; as the film thickness increases, the Seebeck coefficient is increased; 1at% of Ga doping, Seebcek coefficient absolute maximum 74.77μV / K. 6. GZO film having a strong magnetoresistance effect, the reluctance increases with the magnetic field strength and the film mobility increases. The magnetic field strength is 2.15T when, 3at% Ga doped the GZO films magnetoresistive was maximum 0.77%. 7. Integrated optical and electrical properties, proposed the optimum conditions of the deposition GZO films: doping concentration 3at% substrate temperature of 300 ° C, working pressure 2Pa, target-substrate distance 7cm, power 160W. Under this condition, prepared ZnO: Ga film resistivity was 1.44 × 10-3? Cm, average light transmittance at 80% or more, to achieve the performance requirements of the transparent conductive film.