Growth of single crystalline GaN on silver mirrors

GaN films have been grown on highly thermally conducting Ag(111) substrates by using pulsed laser deposition. GaN(0001) grows epitaxially on Ag(111) with an in-plane epitaxial relationship of $\mathrm{Ga}\mathrm{N}\left[11\overline{2}0\right]\Vert \mathrm{Ag}\left[1\overline{1}0\right]$ when low temperature AlN buffer layers are used. The heterointerfaces in the $\mathrm{Al}\mathrm{N}∕\mathrm{Ag}$ structure are atomically abrupt, and that the abruptness remains unchanged during annealing up to $700°\mathrm{C}$ for the GaN growth. Neither 30° rotational domains nor cubic phase domains exist in the GaN films. It has been also confirmed that the GaN films grown on the Ag substrate exhibit strong near band edge photoluminescence emission at $3.51\mathrm{eV}$ . These results indicate that the epitaxial growth of GaN on mirror-polished single crystalline Ag substrates possibly improve the power limits and the light extraction efficiency of future light-emitting devices.