Epitaxial growth of cubic AlN films on SrTiO3(100) substrates by pulsed laser deposition

Cubic AlN thin films have been fabricated on SrTiO3(1 00) substrates by pulsed laser deposition (PLD) at different substrate temperatures and ambient nitrogen pressures. The microstructure and surface morphology of the deposited films were characterized by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectrometry (XPS). AlN films fabricated at 450 degrees C had polycrystalline structures. Epitaxial cubic AlN films were obtained when the deposition temperature was increased to 650 degrees C. The epitaxial relationship of cubic AlN film on SrTiO3 substrate was AlN[100]parallel to SrTiO3[100] and AlN(200)parallel to SrTiO3(100). The degradation of the film crystalline quality was found if the growth temperature was further increased to 800 degrees C. AFM investigation revealed that the surface morphology of AlN films strongly depended on N-2 partial pressure. The root mean square (RMS) roughness values for AlN films deposited at 650 degrees C and at 10Pa N-2 were about 0.674 nm. In addition, XPS results demonstrated that no oxide phase existed in epitaxial AlN films. Thus, epitaxial cubic AlN films could be fabricated on STO substrates under the optional deposition conditions by PLD. (C) 2007 Elsevier B.V. All rights reserved.