Influence of nitrogen-related defects on optical and electrical behaviour in HfO2-xNx deposited by high-power impulse magnetron sputtering

HfO2-xNx films have been deposited by high-power impulse magnetron sputtering in an Ar-O-2-N-2 atmosphere with a series of nitrogen partial pressures. X-ray absorption spectroscopy revealed the optimum deposition conditions required to passivate O vacancies in the HfO2-xNx films by nitrogen. Low-mobility interstitial species prevent crystallisation of nitrogen-incorporated films. These effects combine to remove leakage paths resulting in superior breakdown strengths compared to films deposited without nitrogen. The bandgap was maintained at similar to 5.9 eV in the films in which nitrogen passivated the oxygen vacancies. This is essential to provide sufficient band offsets for HfO2-xNx films to be used an effective gate dielectric. (C) 2015 AIP Publishing LLC.