Epitaxial growth of GaN/Pd/GaN sandwich structure

Abstract

GaN/Pd/GaN sandwich structure was successfully grown by plasma enhanced molecular beam epitaxy on sapphire (0 0 0 1) substrate. Single crystals of Pd and overlayered GaN were confirmed by RHEED and X-ray diffraction. Epitaxial relationship between GaN and Pd was determined as GaN(0 0 0 1)‖Pd(1 1 1)‖GaN(0 0 0 1) and GaN〈1 1 2̄ 0〉‖Pd〈1 1 0〉‖GaN〈1 1 2̄ 0〉. Although no significant intermixing was observed by Auger electron spectroscopy, the sandwiched Pd seems to have a two-dimensional tensile stress caused by the differences in thermal expansion coefficient between Pd and GaN.