Valence band offsets of Sc<inf>x</inf>Ga<inf>1-x</inf>N/AlN and Sc<inf>x</inf>Ga<inf>1-x</inf>N/GaN heterojunctions

The valence band offsets of ScxGa1-xN/AlN heterojunctions were measured by x-ray photoelectron spectroscopy (XPS) and were found to increase from 0.42 eV to 0.95 eV as the Sc content x increased from 0 to 0.15. The increase in valence band offset with increasing x is attributed to the corresponding increase in spontaneous polarization of the wurtzite structure. The ScxGa1-xN/AlN heterojunction is type I, similar to other III-nitride-based heterojunctions. The data also indicate that a type II staggered heterojunction, which can enhance spatial charge separation, could be formed if ScxGa1-xN is grown on GaN.