Reduction of the resistivity of Ag/p-GaN contact by progressive breakdown of the interfacial contamination layer

Ag contact was prepared on p-GaN that had been previously activated by annealing and then removing an Ag/Ni contact. The non-annealed Ag contact showed higher resistivity than the annealed Ag/Ni contact. But, we found that the resistivity of the Ag contact decreases gradually under an electrical stress. Through secondary ion mass spectroscopy analysis, we excluded the effect of enhancement of the holes concentration by the electrical stress and attributed the decrease of resistivity to the progressive breakdown of the contamination layer at the Ag/GaN interface. Our findings provide a way to obtain low-resistivity non-annealed Ag contact to p-GaN.