Highly transparent and conductive group IV impurity-doped ZnO thin films prepared by radio frequency magnetron sputtering

Highly transparent and conducting group IV impurity-doped ZnO thin films have been prepared on low-temperature substrates below 140 °C by rf magnetron sputtering. Resistivities of 4–8×10−4 Ω cm and an average transmittance above 85% in the visible range were obtained for ZnO films doped with Si, Ge, Ti, Zr, or Hf. The stability of resistivity for use in high-temperature atmospheres was significantly improved by the impurity doping. On the contrary, the resistivity of ZnO films doped with Sn or Pb was higher than that of an undoped ZnO film, and these films were discolored.