Research Of AZO For Thin Film Solar Cells

Zinc oxide (ZnO) has attracted considerable attention in the past three decades due toits unique combination of high transparency and low resistivity. ZnO-based transparentconductive film became popular after1980. The most widely used is Al-doped ZnO (AZO)films at present. It is also considered to be the most potential transparent conductive oxide(TCO), which is expected to be the alternative of the indium tin oxides (ITO).As a new semiconductor film material, application of AZO is still in the researchstage, and its performance is needed to be improved to prepare thin film with betterproperties. In this paper AZO thin films were manufactured by radio frequency (RF)magnetron sputtering and the influence factors during the process were analyzed: thesubstrate temperature and the sputtering power. The performance of film is examined indifferent ways such as film structure, electrical properties, optical properties and surfacemorphology. Then some samples were corroded on to obtain the pyramid structure.Then, the effects of Ar flow, RF sputtering power and substrate temperature on AZO’soptical band gap are discussed. Secondly, the correlation of optical band gap and carrierconcentration is then deduced by the modulation of the optical band gap by changing thedeposition parameters. Then as-prepared AZO thin films with different transmittance wereobtained, which can be used to figure out the band gap that varied from3.28to3.88eV asa result. Comparing the band gap to carrier concentration, it was found that the band gapwas proportional to carrier concentration in a certain range.And then the application of obtained AZO thin film to flexible thin film amorphoussilicon (a-Si) solar cells was introduced, which has been the hot spot of research due tolow cost and flexibility of this kind of solar cells. The deposition method is PlasmaEnhanced Chemical Vapor Deposition (PECVD). Firstly, AZO films with pyramidstructure were introduced to a-Si solar cells as window layer. And found that AZO filmwith pyramid structure can improve the efficiency of solar cell. Then AZO film depositedwith different RF powers and substrate temperatures were applied to flexible solar cells toinvestigate the influence of transmission and band gap on the performance of solar cells.