Electrical properties and deep traps spectra of a-plane GaN films grown on r-plane sapphire

A. Y. Polyakov, N. B. Smirnov, A. V. Govorkov, A. V. Markov, Q. Sun, Y. Zhang, C. D. Yerino, Tsung-Shine Ko, I. H. Lee, J. Han

Research output: Contribution to journalArticle

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Abstract

Electrical properties, deep traps spectra and luminescence spectra were studied for two undoped a-plane GaN (a-GaN) films grown on r-plane sapphire using metalorganic chemical vapor deposition and differing by structural perfection. For sample A, the a-GaN film was directly deposited on AlN buffer. A two-step growth scheme was implemented for sample B, including an initial islanding growth stage and a subsequent enhanced lateral growth. Preliminary detailed X-ray analysis showed that the stacking faults density was 8 × 105 cm-1 for sample A and 1.7 × 105 cm-1 for sample B. Electrical properties of a-GaN films were largely determined by deep traps with a level near Ec -0.6 eV, with other prominent traps having the activation energy of 0.25 eV. The Fermi level was pinned by the Ec -0.6 eV deep traps for sample A, but shifted to the vicinity of the shallower 0.25 eV traps for sample B, most likely due to the reduced density of the 0.6 eV traps. This decrease of deep traps density is accompanied by a very pronounced improvement in the overall luminescence intensity. A correlation of the observed improvement in deep traps spectra and luminescence efficiency with the improved crystalline quality of the films is discussed.

Original languageEnglish
Pages (from-to)220-224
Number of pages5
JournalMaterials Science and Engineering B: Solid-State Materials for Advanced Technology
Volume166
Issue number3
DOIs
Publication statusPublished - 2010 Feb 15

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Aluminum Oxide
Sapphire
sapphire
Electric properties
electrical properties
traps
Luminescence
X ray analysis
Stacking faults
Metallorganic chemical vapor deposition
luminescence
Fermi level
Buffers
Activation energy
Crystalline materials
crystal defects
metalorganic chemical vapor deposition
buffers
activation energy

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Polyakov, A. Y. ; Smirnov, N. B. ; Govorkov, A. V. ; Markov, A. V. ; Sun, Q. ; Zhang, Y. ; Yerino, C. D. ; Ko, Tsung-Shine ; Lee, I. H. ; Han, J. / Electrical properties and deep traps spectra of a-plane GaN films grown on r-plane sapphire. In: Materials Science and Engineering B: Solid-State Materials for Advanced Technology. 2010 ; Vol. 166, No. 3. pp. 220-224.
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Electrical properties and deep traps spectra of a-plane GaN films grown on r-plane sapphire. / Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Markov, A. V.; Sun, Q.; Zhang, Y.; Yerino, C. D.; Ko, Tsung-Shine; Lee, I. H.; Han, J.

In: Materials Science and Engineering B: Solid-State Materials for Advanced Technology, Vol. 166, No. 3, 15.02.2010, p. 220-224.

Research output: Contribution to journalArticle

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T1 - Electrical properties and deep traps spectra of a-plane GaN films grown on r-plane sapphire

AU - Polyakov, A. Y.

AU - Smirnov, N. B.

AU - Govorkov, A. V.

AU - Markov, A. V.

AU - Sun, Q.

AU - Zhang, Y.

AU - Yerino, C. D.

AU - Ko, Tsung-Shine

AU - Lee, I. H.

AU - Han, J.

PY - 2010/2/15

Y1 - 2010/2/15

N2 - Electrical properties, deep traps spectra and luminescence spectra were studied for two undoped a-plane GaN (a-GaN) films grown on r-plane sapphire using metalorganic chemical vapor deposition and differing by structural perfection. For sample A, the a-GaN film was directly deposited on AlN buffer. A two-step growth scheme was implemented for sample B, including an initial islanding growth stage and a subsequent enhanced lateral growth. Preliminary detailed X-ray analysis showed that the stacking faults density was 8 × 105 cm-1 for sample A and 1.7 × 105 cm-1 for sample B. Electrical properties of a-GaN films were largely determined by deep traps with a level near Ec -0.6 eV, with other prominent traps having the activation energy of 0.25 eV. The Fermi level was pinned by the Ec -0.6 eV deep traps for sample A, but shifted to the vicinity of the shallower 0.25 eV traps for sample B, most likely due to the reduced density of the 0.6 eV traps. This decrease of deep traps density is accompanied by a very pronounced improvement in the overall luminescence intensity. A correlation of the observed improvement in deep traps spectra and luminescence efficiency with the improved crystalline quality of the films is discussed.

AB - Electrical properties, deep traps spectra and luminescence spectra were studied for two undoped a-plane GaN (a-GaN) films grown on r-plane sapphire using metalorganic chemical vapor deposition and differing by structural perfection. For sample A, the a-GaN film was directly deposited on AlN buffer. A two-step growth scheme was implemented for sample B, including an initial islanding growth stage and a subsequent enhanced lateral growth. Preliminary detailed X-ray analysis showed that the stacking faults density was 8 × 105 cm-1 for sample A and 1.7 × 105 cm-1 for sample B. Electrical properties of a-GaN films were largely determined by deep traps with a level near Ec -0.6 eV, with other prominent traps having the activation energy of 0.25 eV. The Fermi level was pinned by the Ec -0.6 eV deep traps for sample A, but shifted to the vicinity of the shallower 0.25 eV traps for sample B, most likely due to the reduced density of the 0.6 eV traps. This decrease of deep traps density is accompanied by a very pronounced improvement in the overall luminescence intensity. A correlation of the observed improvement in deep traps spectra and luminescence efficiency with the improved crystalline quality of the films is discussed.

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