On the presence of Ga 2 O sub-oxide in high-pressure water vapor annealed AlGaN surface by combined XPS and first-principles methods

College

College of Science

Department/Unit

Physics

Document Type

Article

Source Title

Applied Surface Science

Volume

481

First Page

1120

Last Page

1126

Publication Date

7-1-2019

Abstract

© 2019 Elsevier B.V. We conducted X-ray photoelectron spectroscopy (XPS) and first-principles calculations based on density functional theory (DFT) to confirm the presence of Ga 2 O sub-oxide in high-pressure water vapor annealed AlGaN surface. We note that the Ga 3d XPS peak broadens and shifts towards higher binding energies, which suggests surface oxide formation. Deconvoluted Ga 3d XPS profiles between HPWVA-treated and reference samples reveal reasonable inclusion of Ga 2 O peak, suggesting formation of Ga 2 O sub-oxide. To theoretically confirm the presence of Ga 2 O, we calculated the Ga 3d core-level shift using initial state approximation. We obtained a 0.74 eV shift, in reasonable agreement with that of Ga 2 O. Moreover, based on the calculation of net charge on Ga using DFT, we also obtained a +1 oxidation state for Ga, indicating its existence in Ga 2 O form. By combining theory and experiment, therefore, we have explored the possibility of the formation of Ga 2 O sub-oxide, which may provide new avenues for obtaining highly stable operation in GaN-based devices.

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Digitial Object Identifier (DOI)

10.1016/j.apsusc.2019.03.196

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