Structural, electrical and optical properties of zirconium-doped zinc oxide films prepared by radio frequency magnetron sputtering

Transparent and conducting zirconium-doped zinc oxide films have been prepared by radio frequency magnetron sputtering at room temperature. The ZrO₂ content in the target is varied from 0 to 10 wt.%. The films are polycrystalline with a hexagonal structure and a preferred orientation along the c axis. As the ZrO₂ content increases, the crystallinity and conductivity of the film are initially improved and then both show deterioration. Zr atoms mainly substitute Zn atoms when the ZrO₂ content are 3 and 5 wt.%, but tend to cluster into grain boundaries at higher contents. The lowest resistivity achieved is 2.07 × 10^− 3 Ω cm with the ZrO₂ content of 5 wt.% with a Hall mobility of 16 cm² V^− 1 s^− 1 and a carrier concentration of 1.95 × 10²⁰ cm^− 3. All the films present a high transmittance of above 90% in the visible range. The optical band gap depends on the carrier concentration, and the value is larger at higher carrier concentration.