Fabrication and Properties of Amorphous Zinc Oxynitride Thin Films

Zn-O-N thin films fabricated by reactive radio frequency magnetron sputtering have been investigated for their compositional, structural, transport and optical properties. In contrast to processes in which the reaction for either the oxide or the nitride is dominant, the multireaction process yields a substantially amorphous films with the Hall mobility within the range from 15 to 80 cm²/(V s). In addition, it has been observed that the Hall mobility increases for Zn-O-N. Since it has a narrower bandgap than ZnO, it is put forward that the high mobility is due to the valence band maximum in this material lying above the trap states in the gap commonly observable in ZnO. These traps originate from oxygen vacancies and are localized at the bottom of the band gap influencing the carrier mobility.