Influence of DC magnetron sputtering parameters on the properties of amorphous indium zinc oxide thin film

Abstract Amorphous or crystalline indium zinc oxide (IZO) thin films, which are highly transparent and conducting, were deposited by DC magnetron sputtering. X-Ray diffraction technique was used for analyzing microstructures of the films, and also differential thermal analysis was performed for observing their crystallization behavior. The IZO thin films prepared were crystallized at much higher temperature than ITO films were. The crystallized samples showed (222) preferred orientations. By varying process parameters, the optimum conditions for the highest electrical conductivity and optical transmittance, and the lowest surface roughness were found. The resistivity of IZO films decreased as the deposition temperature increased until 250 °C, but sharp rise occurred at or above 300 °C. The extinction coefficients diminished in the films prepared with the conditions of higher deposition temperature, sputtering gas of light mass, and heat treatment. However, excessive amount of oxygen flow during deposition brought about the increase of the extinction coefficients. The variations of extinction coefficients mainly influenced the transmittance of the samples. On the basis of X-ray photoelectron spectroscopy analysis, atomic force microscopy measurement, spectroscopic ellipsometry and spectrophotometer measurement, several characteristics of IZO thin films were discussed comparing with those of ITO thin films. Very low surface roughness of IZO thin films could satisfy the requirement for organic light-emitting diode.