Abstract
The epitaxial growth of GaN on Si (1 1 1) substrates has been performed using plasma-assisted molecular beam epitaxy with a thin (∼19.3 nm) single-crystal layer of Sc 2 O 3 as a template/buffer layer. The structural properties and in situ epitaxial growth were studied using reflection high energy electron diffraction (RHEED), high-resolution transmission electron microscopy, and high-resolution X-ray diffraction. An orientation relationship of GaN(0 0 0 2)∥Sc 2 O 3 (1 1 1)∥Si(1 1 1) and GaN[1 0 1̄ 0]∥Sc 2 O 3 [4 2̄ 2̄] off 60° with Si[4 2̄ 2̄] was determined. The excellent growth of Sc 2 O 3 on Si and GaN on Sc 2 O 3 was achieved, as observed from streaky and bright RHEED patterns. The Sc 2 O 3 template serves as an effective barrier layer preventing diffusion of Si and Ga during the GaN growth at high temperatures under nitrogen plasma. No cracking was observed in the GaN layer with thickness around 0.2 μm when inspected with an optical microscope. © 2008 Elsevier B.V. All rights reserved.