The Effects of Solvents to ZnO:Al Transparent Conductive Thin Films Synthesized by Sol-Gel Method

The purpose of this study was to discuss the effects of different solvent systems for aluminum doped zinc oxide (AZO) thin film deposition by using the sol-gel method. In the conventional sol-gel method of producing AZO thin films, the solution selected as the precursor solvent was used ethylene glycol monomethylether (EGME), which in this study propylene glycol mono-methyl ether (PGME) was used. The precursor solution was observed by TGA/DSC to understand the variations while heating. The two prepared precursor solutions were then respectively spin coated onto substrates of boron silicate glass. XRD analysis indicated both showed significant c-axis preferred orientation. The surface morphology of the films was observed by FESEM, which showed that the thin film surface by PGME solvent was smoother and dense. A four-point probe was used to measure the electrical resistance of the thin films, which the measured results indicated that the thin film produced by PGME had lower resistivity than those produced by EGME. Resulting with a thin film electric resistance reaching as low as 3.474×10-3(W×cm). The visible light transparency was determined via UV-vis analysis. Results showed that the average transparency of thin films produced by the EGME solvent reached 95% and above, where the average transparency from PGME solvent still reached 90% and above. Experimental results demonstrated that PGME is a good option to synthesize AZO thin films.