Growth of atomically smooth cubic AlN by molecular beam epitaxy

Abstract

In this work we present the growth of atomically flat c‐AlN layers (surface roughness 0.3 nm RMS) by plasma assisted molecular beam epitaxy (PAMBE) on 3C‐SiC. We develop a model for Al surface kinetics that correlates with RHEED intensity vs. time measurements. We show RHEED patterns and atomic force microscopy (AFM) scans emphasizing the quality of the layers.Ellipsometry yields the dielectric function of c‐AlN around the adsorption edge. The direct gap is obtained with 5.93 eV at room temperature, while the indirect one is below 5.3 eV (onset of adsorption) (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

MBE growth of cubic AlN on 3C‐SiC substrate

“…More details concerning the cleaning process can be found in Ref. 8. Because of its metastable nature, exposing a c‐AlN surface to nitrogen leads to the formation of hexagonal clusters.…”

“…Growing Al rich c‐AlN with 1 ML Al surface coverage can prevent hexagonal condensation. A model linking the Al surface coverage and RHEED intensity has been developed to maintain 1 ML Al coverage 8, 9.…”

Influence of Al x Ga1−x N nucleation layers on MOVPE-grown zincblende GaN epilayers on 3C-SiC/Si(001)

“…The difficulties in achieving zb phase purity for the AlN growth on 3C-SiC (001) at low-or high temperature [21] were ascribed to the relative stability of the zb and wz phases of AlN and GaN as outlined by Städele et al [33] who calculated a total energy difference between the zb and wz phases in AlN of 28.9 meV atom −1 compared to 10.2 meV atom −1 in GaN. Although the growth of AlN may be energetically less favourable than GaN on 3C-SiC, As et al [17,34] successfully grew high-quality zb-Al x Ga 1−x N films by MBE after a careful cleaning routine of the substrate surface. Encouraged by these recent results, we investigate here the use of zb-Al x Ga 1−x N NLs for zb-GaN growth on 3C-SiC (001) by MOVPE, focussing on the phase purity and surface morphology of the resulting epitaxial layers.…”