Epitaxial growth of AlN on Cu(1 1 1) substrates using pulsed laser deposition

We have succeeded in the epitaxial growth of AlN on Cu(1 1 1) substrates using pulsed laser deposition (PLD) for the first time. We achieved atomically flat surfaces of Cu(1 1 1) by annealing in an ultra high vacuum chamber. In situ X-ray photoelectron spectroscopy and reflection high-energy electron diffraction studies revealed that the native oxide layers on the surfaces had been successfully removed and that the Cu surfaces were reformed by the segregation of antimony atoms, incorporated in the substrates as impurities. We found that AlN (0 0 0 1) grows epitaxially on Cu(1 1 1) at a substrate temperature of as low as 500 °C with in-plane epitaxial relationships of AlN[112¯0]//Cu[11¯0]. Electron backscattering diffraction measurements showed that neither 30° rotational domains nor cubic phase domains exist in the AlN films. Spectroscopic ellipsometry measurements revealed that no interfacial layers exist at the AlN/Cu hetero interfaces within the limits of detection. These results indicate that the PLD low-temperature growth technique permits the preparation of high-quality AlN expitaxial films on single-crystal metal substrates.