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

We reveal the existence of interfacial, epitaxial, Pd grains in an as-depos ited Pd film evaporated on GaN(0001) at room temperature. The crystallizati on of the remnant, disordered Pd was caused by the growth of the interfacia l grains during annealing up to 600 degrees 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 Ga2Pd5 and Ga5Pd gal lides in epitaxial relationships with GaN at higher a temperature of 700 de grees C. (C) 2000 The Electrochemical Society. S1099-0062(00)00-02-067-8. A ll rights reserved.