Mitsuaki Oya

Low Contact Resistance P-Type Electrode for Nonpolar m-Plane GaN

A low contact resistance p-type electrode for nonpolar m-plane GaN was obtained using Mg as the electrode material. Ga atoms diffused toward the Mg electrode after heat treatment. Because the Ga vacancies act as acceptors and form levels in the Schottky barrier, we consider hopping conduction through the Ga vacancy levels to be the main mechanism for the formation of the p-type ohmic contact to m-plane GaN. The specific contact resistance was reduced to 8×10-4 Ω cm2 by optimizing the heat treatment temperature and the Mg thickness. A significant reduction in the operating voltage of m-plane GaN LEDs was achieved by using this electrode technology.