Two-domain formation during the epitaxial growth of GaN (0001) on c-plane Al 2O 3 (0001) by high power impulse magnetron sputtering
Journal
Journal of Applied Physics
Journal Volume
110
Journal Issue
12
Date Issued
2011
Author(s)
Junaid, M.
Lundin, D.
Palisaitis, J.
Hsiao, C.-L.
Darakchieva, V.
Jensen, J.
Persson, P.O.Å.
Sandström, P.
Lai, W.-J.
Chen, K.-H.
Helmersson, U.
Hultman, L.
Birch, J.
Abstract
We study the effect of high power pulses in reactive magnetron sputter epitaxy on the structural properties of GaN (0001) thin films grown directly on Al 2O 3 (0001) substrates. The epilayers are grown by sputtering from a liquid Ga target, using a high power impulse magnetron sputtering power supply in a mixed N 2/Ar discharge. X-ray diffraction, micro-Raman, micro-photoluminescence, and transmission electron microscopy investigations show the formation of two distinct types of domains. One almost fully relaxed domain exhibits superior structural and optical properties as evidenced by rocking curves with a full width at half maximum of 885 arc sec and a low temperature band edge luminescence at 3.47 eV with the full width at half maximum of 10 meV. The other domain exhibits a 14 times higher isotropic strain component, which is due to the higher densities of the point and extended defects, resulting from the ion bombardment during growth. Voids form at the domain boundaries. Mechanisms for the formation of differently strained domains, along with voids during the epitaxial growth of GaN are discussed. © 2011 American Institute of Physics.
Publisher
American Institute of Physics
Type
journal article