Fluorine thermal stability of ZnO:F films investigated by thermal desorption spectroscopy

To estimate the fluorine thermal stability of fluorine doped zinc oxide (ZnO:F) films, ZnO:F films were prepared by co-sputtering zinc oxide(ZnO) and magnesium fluoride (MgF₂) targets under different sputtering powers. The prepared films were tested with a thermal desorption system heated from room temperature to 500degC. Four elements: zinc (Zn), oxygen (O), magnesium (Mg) and fluorine (F) from ZnO:F films exhibit clear and similar thermal desorption behavior. The result indicates prepared ZnO:F films will desorb corresponding to low bound strength under 100degC heat treatment, and exhibit multilayer instead of layer by layer desorption behavior based on Polanyi-Wigner model. Fluorine is thermally unstable for ZnO:F films evidenced by thermal desorption test. Electrical and optical properties of ZnO:F films after thermal desorption test become negative. This work contributes to display or solar industry if ZnO:F films are considered to be the transparent conductive oxide films.