Study Of Al Doped ZnO Films Grown By PLD At High Temperature

ZnO is a semiconductor material with excellent photoelectric properties, which has a wide application prospect in many fields. A1doped ZnO (AZO) transparent conductive thin film is a hot topic in ZnO research field. Because of its high transmittance, high conductivity, low price, abundant and non-toxic, AZO becomes the most promising TCO material to replace ITO.In this dissertation, we study the Al-doped ZnO (AZO) films deposited on c-axis sapphire and quartz substrates by using pulsed laser deposition (PLD) method. The surface morphology, crystal quality, optical and electrical properties of the films are characterized with atomic force microscopy, x-ray diffraction, transmission spectra and four-point probe resistivity measurement. The influence of the deposition temperature and oxygen pressure on the film growth and optoelectronic properties are studied. The conclusions are as following.1. With the increase of temperature, the grain size of AZO film becomes larger. At800℃, film’s roughness increases slightly, but it still belongs to the atomically smooth. All samples were c axis orientation and have a good epitaxial relation with the sapphire substrate. The crystallinity of the films is improved greatly with the increase of temperature. The optical band gap decreases with the increasing deposition temperature. All the films have a high transmittance, especially the sample prepared at800℃, in the visible light region, its average transmittance is higher than95%. With the increase of growth temperature, the resistivity of the films increased, but at800℃, AZO film’s resistivity is still in a low level.2. With increasing the oxygen partial pressure, the grain size becomes larger and the surface roughness increases, but still keep at a level of atomic smooth. All samples were c axis orientation and have a good epitaxial relation with the sapphire substrate. The film which grown at0.1Pa has the best crystallinity. The effect of oxygen partial pressure on the ultraviolet absorption edge of the films is very small. All the samples have a high transmittance in the visible region. The film made at0.1Pa has the highest transmittance, close to95%. With the oxygen partial pressure increases, the resistance of the films first decrease then increase. In high deposition temperature of800℃, there is an optimum deposition conditions at about0.1Pa, AZO films deposited at this pressure have the lowest resistivity, about2.73mQ·cm. It can fully satisfy the requirements of ZnO optoelectronic devices’electrodes.