Strong effect of scandium source purity on chemical and electronic properties of epitaxial ScxAl1xN/GaN heterostructures

Published In:
APL Materials
Volume: 9
Issue: 9
Publication Date: Sep 1, 2021
Authors: Joseph Casamento, Hyunjea Lee, Celesta S. Chang, Matthew F. Besser, Takuya Maeda, David A. Muller, Huili (Grace) Xing, Debdeep Jena

DOI: 10.1063/5.0054522


Epitaxial multilayer heterostructures of ScxAl1−xN/GaN with Sc contents x = 0.11–0.45 are found to exhibit significant differences in structural quality, chemical impurity levels, and electronic properties depending on the starting Sc source impurity levels. A higher purity source leads to a 2–3 orders of magnitude reduction in the carbon, oxygen, and fluorine unintentional doping densities in MBE-grown ScxAl1−xN/GaN multilayers. Electrical measurements of ScxAl1−xN/n+GaN single heterostructure barriers show a 5–7 orders of magnitude reduction in the electrical leakage for films grown with a higher purity Sc source at most Sc contents. The measured chemical and electrical properties of epitaxial ScxAl1−xN highlight the importance of the starting Sc source material purity for epitaxial device applications that need these highly piezoelectric and/or ferroelectric transition-metal nitride alloys.

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