Comparative study on MOCVD growth of a-plane GaN films on r-plane sapphire substrates using GaN, AlGaN, and AlN buffer layers

J. N. Dai, Z. H. Wu, C. H. Yu, Q. Zhang, Y. Q. Sun, Y. K. Xiong, X. Y. Han, L. Z. Tong, Q. H. He, Fernando Ponce, C. Q. Chen

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

In this work, we have comparatively investigated the effects of the GaN, AlGaN, and AlN low-temperature buffer layers (BL) on the crystal quality of a-plane GaN thin films grown on r-plane sapphire substrates. Scanning electron microscopy images of the a-plane GaN epilayers show that using an AlGaN BL can significantly reduce the density of surface pits. The full-width at half-maximum values of the (112̄0) x-ray rocking curve (XRC) are 0.19°, 0.36°, and 0.48° for the films grown using Al 0.15Ga 0.85N, GaN, and AlN BLs, respectively, indicating that an AlGaN BL can effectively reduce the mosaicity of the films. Room-temperature photoluminescence shows that the AlGaN BL results in lower impurity incorporation in the subsequent a-plane GaN films, as compared with the case of GaN and AlN BLs. The higher crystal quality of a-plane GaN films produced by the Al 0.15Ga 0.85N BL could be due to improvement of BL quality by reducing the lattice mismatch between the BL and r-sapphire substrates, while still keeping the lattice mismatch between the BL and epitaxial a-plane GaN films relatively small.

Original languageEnglish (US)
Pages (from-to)1938-1943
Number of pages6
JournalJournal of Electronic Materials
Volume38
Issue number9
DOIs
StatePublished - Sep 2009

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Aluminum Oxide
Metallorganic chemical vapor deposition
Buffer layers
Sapphire
metalorganic chemical vapor deposition
sapphire
buffers
Substrates
Lattice mismatch
Crystals
aluminum gallium nitride
Epilayers
Full width at half maximum
crystals
Photoluminescence
Impurities
photoluminescence
X rays
Thin films
impurities

Keywords

  • A-Plane GaN
  • Metalorganic chemical vapor deposition (MOCVD)
  • Photoluminescence (PL)
  • Raman
  • Scanning electron microscope (SEM)
  • X-ray diffraction (XRD)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Materials Chemistry

Cite this

Comparative study on MOCVD growth of a-plane GaN films on r-plane sapphire substrates using GaN, AlGaN, and AlN buffer layers. / Dai, J. N.; Wu, Z. H.; Yu, C. H.; Zhang, Q.; Sun, Y. Q.; Xiong, Y. K.; Han, X. Y.; Tong, L. Z.; He, Q. H.; Ponce, Fernando; Chen, C. Q.

In: Journal of Electronic Materials, Vol. 38, No. 9, 09.2009, p. 1938-1943.

Research output: Contribution to journalArticle

Dai, J. N. ; Wu, Z. H. ; Yu, C. H. ; Zhang, Q. ; Sun, Y. Q. ; Xiong, Y. K. ; Han, X. Y. ; Tong, L. Z. ; He, Q. H. ; Ponce, Fernando ; Chen, C. Q. / Comparative study on MOCVD growth of a-plane GaN films on r-plane sapphire substrates using GaN, AlGaN, and AlN buffer layers. In: Journal of Electronic Materials. 2009 ; Vol. 38, No. 9. pp. 1938-1943.
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AU - Wu, Z. H.

AU - Yu, C. H.

AU - Zhang, Q.

AU - Sun, Y. Q.

AU - Xiong, Y. K.

AU - Han, X. Y.

AU - Tong, L. Z.

AU - He, Q. H.

AU - Ponce, Fernando

AU - Chen, C. Q.

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AB - In this work, we have comparatively investigated the effects of the GaN, AlGaN, and AlN low-temperature buffer layers (BL) on the crystal quality of a-plane GaN thin films grown on r-plane sapphire substrates. Scanning electron microscopy images of the a-plane GaN epilayers show that using an AlGaN BL can significantly reduce the density of surface pits. The full-width at half-maximum values of the (112̄0) x-ray rocking curve (XRC) are 0.19°, 0.36°, and 0.48° for the films grown using Al 0.15Ga 0.85N, GaN, and AlN BLs, respectively, indicating that an AlGaN BL can effectively reduce the mosaicity of the films. Room-temperature photoluminescence shows that the AlGaN BL results in lower impurity incorporation in the subsequent a-plane GaN films, as compared with the case of GaN and AlN BLs. The higher crystal quality of a-plane GaN films produced by the Al 0.15Ga 0.85N BL could be due to improvement of BL quality by reducing the lattice mismatch between the BL and r-sapphire substrates, while still keeping the lattice mismatch between the BL and epitaxial a-plane GaN films relatively small.

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