Effect of Cu dopant on microstructure and phase transformation of ZnTiO3 thin films prepared by radio frequency magnetron sputtering

Abstract

Cu doped zinc titanate (ZnTiO3) films were prepared using radio frequency magnetron sputtering. Subsequent annealing of the as-deposited films was performed at temperatures ranging from 600 to 900°C. It was found that the as-deposited films were amorphous and contained 0.84at.% Cu. This was further confirmed by the onset of crystallization that took place at annealing temperatures 600°C. The phase transformation for the as-deposited films and annealed films was investigated in this study. The results showed that Zn2Ti3O8, ZnTiO3, and TiO2 can coexist at 600°C. When annealed at 700°C, the results revealed that mainly the hexagonal ZnTiO3 phase formed, accompanied by minority amounts of TiO2 and Zn2Ti3O8. Unlike pure zinc titanate films, this result showed that the Zn2Ti3O8 phase can be stable at temperatures above 700°C. Moreover, Cu addition in zinc titanate thin film could result in the decomposition of hexagonal (Zn,Cu) TiO3 phase at 800°C. When the Cu content was increased in zinc titanate thin films from 0.84at.% to 2.12at.%, there were only two phases; Zn2Ti3O8 and ZnTiO3, coexisting at temperatures between 700 and 800°C. This result indicated that a greater presence of Cu dopants in zinc titanate thin films leads to the existence of the Zn2Ti3O8 phase at higher temperatures.