Epitaxial growth of AlN and GaN on Si(111) by plasma-assisted molecular beam epitaxy

Epitaxial wurtzite aluminum nitride (AIN) and gallium nitride (GaN) films have been grown on Si(1 1 1) by plasma-assisted molecular beam epitaxy (PA-MBE). Two-dimensional growth (2DG) of single-crystalline AIN films is achieved on Si(1 1 1) near stoichiometric supply of aluminum and atomic nitrogen. Two distinct categories of AIN-surface reconstructions have been observed. GaN films exhibit 1 x 1 high-energy electron diffraction (RHEED) pattern if grown between 650 degrees C and 770 degrees C substrate temperature on AIN buffers. Stable Ga- and N-adlayer-induced surface reconstructions have been studied below 600 degrees C after the growth. The X-ray diffraction (XRD) pattern show sharp and well separated (0 0 0 1) reflections of wurtzite GaN and AIN indicating complete texture with GaN[0 0 0 1]parallel to AIN[0 0 0 1]parallel to Si[1 1 1 ]. From the determined GaN lattice constant complete strain relaxation can be concluded which is further confirmed by the temperature-dependent photoluminescence (PL) investigations. (C) 1999 Elsevier Science B.V. All rights reserved.