Effects of hydrogen treatment on ohmic contacts to p-type GaN films

► The surface inversion of p-GaN films was successfully achieved by H2 treatment at high temperatures. ► The shifts in the surface Fermi level due to the H2 treatment were identified by XPS measurement. ► The linear I-V behavior of the H2-treated p-GaN films is due to the high VN density pinned the surface Fermi level close to the conduction-band edge. ► The surface inversion by means of H2 treatment can play an important role in lowering the metal contact resistance to p-GaN films.