Schottky barrier and interface chemistry for Ni contacted to Al0.8Ga0.2N grown on c‐oriented AlN single crystal substrates

We demonstrate electronic sequential tunneling transport through the ground‐state subbands of GaN/Al0.15Ga0.85N quantum cascade structures grown on free‐standing GaN substrates. A pronounced transition from a high‐ to a low‐resistance state is observed as the applied voltage is increased. The measured current‐voltage characteristics are found to vary with temperature, structure design, and polarity of the applied bias, in a way that is fully consistent with theoretical expectations. The dominant transport mechanism is determined to be scattering‐assisted tunneling (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)