Epitaxial growth of cubic AlN films on SrTiO 3(1 0 0) substrates by pulsed laser deposition

Abstract

Cubic AlN thin films have been fabricated on SrTiO 3(1 0 0) 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 °C had polycrystalline structures. Epitaxial cubic AlN films were obtained when the deposition temperature was increased to 650 °C. The epitaxial relationship of cubic AlN film on SrTiO 3 substrate was AlN[1 0 0]∥SrTiO 3[1 0 0] and AlN(2 0 0)∥SrTiO 3(1 0 0). The degradation of the film crystalline quality was found if the growth temperature was further increased to 800 °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 °C and at 10 Pa 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.