Structural evolution of Pd/GaN(0001) films during postannealing

초록

We reveal the existence of interfacial, epitaxial, Pd grains in an as-deposited Pd film evaporated on GaN(0001) at room temperature. The crystallization of the remnant, disordered Pd was caused by the growth of the interfacial grains during annealing up to 600 °C. The origin of the Pd epitaxy on GAN(0001) was attributed to a 6/7 matched interface structure, wherein 6-Ga atomic distances match 7-Pd atomic distances. Remarkably, the Pd film was, by the Pd-Ga reaction, completely transformed to Ga<inf>2</inf>Pd<inf>5</inf> and Ga<inf>5</inf>Pd gallides in epitaxial relationships with GaN at higher a temperature of 700 °C.