Epitaxial growth of GaN on copper substrates

We have grown GaN films on Cu(111) substrates using pulsed laser deposition. We have found that GaN(0001) grows epitaxially on Cu(111) when employing low temperature grown AlN buffer layers with an in-plane epitaxial relationship of AlN[11 (2) over bar0]parallel to Cu[1 (2) over bar0] Reflection high-energy electron diffraction images have exhibited sharp streaky patterns, indicating that GaN grows with a flat surface. Electron backscattering diffraction observations have revealed that neither 30 degrees rotational domains nor cubic phase domains exist in the GaN films. Spectroscopic ellipsometry measurements have shown that the heterointerfaces in the GaN/AlN/Cu structure are abrupt. The epitaxial growth of GaN on Cu substrates is likely to raise the power limit for future light emitting and electron devices due to the high thermal conductivity of Cu.