We report on the formation of low resistivity ohmic contacts to p-GaN, rc<10-4Wcm2, by increasing the concentration of the active Mg in the subcontact zone, via Zr-mediated release of hydrogen.

Microstructure and thermal stability of ZrN/ZrB2 bilayer deposited on GaN have been studied using transmission electron microscopy methods (TEM) and secondary ion mass spectrometry (SIMS). It has been demonstrated that annealing of the contact structure at 11000C in N2 atmosphere does not lead to any observable metal/ semiconductor interaction. In contrast, a failure of the integrity of ZrN/ZrB2 metallization at 8000C, when the heat treatment is performed in O2 ambient has been observed.