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Determination of surface barrier height and surface state density in GaN films grown on sapphire substrates

Published online by Cambridge University Press:  01 February 2011

Seong-Eun Park ,
Joseph J. Kopanski ,
Youn-Seon Kang ,
Lawrence H. Robins  and
Hyun-Keel Shin
Seong-Eun Park
Affiliation:
Semiconductor Electronics Division, National Institute of Standards and Technology Gaithersburg, MD 20899–8120
Joseph J. Kopanski
Affiliation:
Semiconductor Electronics Division, National Institute of Standards and Technology Gaithersburg, MD 20899–8120
Youn-Seon Kang
Affiliation:
Ceramics Division, National Institute of Standards and Technology Gaithersburg, MD 20899–8520
Lawrence H. Robins
Affiliation:
Ceramics Division, National Institute of Standards and Technology Gaithersburg, MD 20899–8520
Hyun-Keel Shin
Affiliation:
Gwangju Techno Park, LED/LD Packaging Service Center, 958–3 Daechon-dong, Buk-gu, Gwangju 500–706, South Korea
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Abstract

Photoreflectance (PR) modulation spectroscopy was performed to investigate surface properties of GaN films grown on sapphire substrates. From the period of the Franz-Keldysh oscillations, the surface electric field across the GaN space charge region was found to be (197 ± 11) kV/cm, which corresponds to a surface state density of 1.0×1012 cm−2. A surface barrier height of 0.71 eV was determined by fitting the dependence of the PR intensities on pump beam power density. We suggest that a deep level is formed at 2.68 eV above the GaN valence band edge due to the large density of surface states.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 831: Symposium E – GaN, AlN, InN, and Their Alloys , 2004 , E3.2
Copyright
Copyright © Materials Research Society 2005

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References

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