Characterization of al-doped conductive layer of ZnO thin film solar cell

Abstract

Zinc Oxide (ZnO) is a group II-VI semiconductor thin film with a hexagonal wurtzite crystal structure. Its direct wide band gap of Eg= 3.2~3.7eV, low electrical resistivity, high optical transmittance characteristics within the visible range and high resistance to degradation under normal operating conditions. These characteristics distinct itself from other semiconductors with similar crystal structure to widely use in optoelectronic industries. ZnO doped with impurity is a potential choice for transparent conducting oxide (TCO) in commercial area as a transparent electrode in flat panel displays (FPDs) and solar cells. As it is regarded a good transparent conductive oxide (TCO) due to its opto-electro properties, non-toxicity, relatively abundance and low cost; Attention of this is to analyze materials thickness, surface morphology, electrical characteristics, crystal structure and orientation. In execution to this purpose, the sol-gel process of producing Zinc Oxide (ZnO) has chosen which is doped by impurities of Aluminum (Al) to make Al doped Zinc Oxide (Zno:Al) on a glass substrate, using 2-methoxyethanol as solvents and monoethanolamine (MEA) as stabilizer. This combination further increases its optical transmittance and band gap of the thin film material. The sole purpose was to optimize the characteristics of this material by focusing on its several characteristics followed by changing the duration of solution preparation, changing the deposition level on substrates, variation in annealing atmosphere and temperature to observe the characteristics changes occurred in the film. In each stage of observation significant characteristics of the film have found which the main execution of this thesis.