Influence of High-temperature AlN Intermediate Layer on the Optical Properties of MOCVD Grown AlGaN Films

Abstract

By combining spectroscopic ellipsometry (SE) and optical transmission (OT) characterization methods we have systematically investigated the in uence of AlN intermediate layer and AlN transition layer on the optical properties of AlGaN epilayers grown on sapphire by metalorganic chemical vapor deposition (MOCVD) method. Most dielectric functions of III-nitrides obtained by different research groups show significant band-tail absorption-which is not anticipated for such a direct band gap material. The dielectric functions are studied for a series of AlGaN/AlN/Al2O3 structures, with a four-layer model taking into account both high temperature grown AlN layer and low temperature grown AlN layer. The results obtained by fitting the optical parameters to experimental data show that the band-tail absorption should originate from the transition layer. AlGaN film without high temperature AlN epilayer exhibited a redshift of band gap around 0.24 eV.

Department(s)

Electrical and Computer Engineering

Comments

National Natural Science Foundation of China, Grant 2013GXNSFFA019001

Keywords and Phrases

AlGaN; AlN Epilayer; Optical transmission; Spectroscopic ellipsometry

International Standard Serial Number (ISSN)

2053-1591

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2024 The Authors, All rights reserved.

Creative Commons Licensing

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Publication Date

01 Feb 2017

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