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Published online by Cambridge University Press: 24 February 2015
We investigated the electrical properties of the rf-sputtered HfxZn1-xO/ZnO heterostructures. The thermal annealing on ZnO prior to the HfxZn1-xO deposition greatly influences the properties of the heterostructures. A highly conductive interface formed at the interface between HfxZn1-xO and ZnO thin films as the ZnO annealing temperature exceeded 500°C, leading to the apparent decrease of the electrical resistance. The resistance decreased with an increase of either thickness or Hf content of the HfxZn1-xO capping layer. The Hf0.05Zn0.95O/ZnO heterostructure with a 200-nm-thick 600°C-annealed ZnO exhibits a carrier mobility of 14.3 cm2V-1s-1 and a sheet carrier concentration of 1.93×1013 cm-2; the corresponding values for the bare ZnO thin film are 0.47 cm2V-1s-1 and 2.27×1012 cm-2, respectively. Rf-sputtered HfZnO/ZnO heterostructures can potentially be used to increase the carrier mobility of thin-film transistors in large-area electronics.