Abstract
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.
Highlights
As ScxAl1−xN increases in technological relevance, the purification of Sc is starting to acquire increased relevance
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
We report the differences in the structural and chemical properties of epitaxial, single-crystalline ScxAl1−xN/GaN multilayer heterostructures, where the Sc content is varied between x = 0.11 and 0.45 mole fraction, when grown with two Sc sources of different chemical purity levels
Summary
Cite as: APL Mater. 9, 091106 (2021); doi: 10.1063/5.0054522 Submitted: 19 April 2021 • Accepted: 15 August 2021 • Published Online: 7 September 2021 Joseph Casamento,1,a) Hyunjea Lee,2 Celesta S. Chang,3,4,b) Matthew F. Besser,5 David A. Muller,3,6 Huili (Grace) Xing,1,2,6 and Debdeep Jena1,2,6
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