Characterization of gallium-doped zinc oxide contact on n-type gallium nitride epitaxial layers

Jinn-Kong Sheu, K. H. Chang, M. L. Lee, J. F. Huang, K. S. Kang, W. L. Wang, Wei-Chi Lai, T. H. Hsueh

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

This study demonstrates the electrical characteristics of Ga-doped ZnO (GZO) thin films deposited onto n-type GaN (n-GaN) epitaxial layers with a variety of electron concentrations. The ohmic characteristics could be obtained from the GZO/n-GaN samples after a thermal annealing process was performed at 800°C in a nitrogen atmosphere for 1 min when the n-GaN layers had a carrier concentration of approximately 1× 1019 cm-3. The specific contact resistance (ρ c) was as low as 2.6× 10-4 cm2. The ohmic characteristics can be attributed to the fact that the heavy doping of n-GaN layers and the low resistivity GZO film can result in a carrier transport via a tunneling mechanism at the GZO/GaN interface. However, the GZO/n-GaN samples exhibited nonlinear current-voltage (I-V) characteristics (i.e., a Schottky contact) when the annealing temperature (TA) was lower than or equal to 600°C even though the carrier concentration of n-GaN reached 1× 1019 cm-3. These GZO/n-GaN Schottky contacts were due to the low carrier concentration of GZO films and/or n-GaN layers. The effective Schottky barrier heights of the 700°C annealed GZO/n-GaN (n∼ 1016 cm-3) samples were around 0.73 and 0.75 eV, which were deduced from the I-V and capacitance-voltage characteristics, respectively.

Original languageEnglish
JournalJournal of the Electrochemical Society
Volume156
Issue number8
DOIs
Publication statusPublished - 2009 Jul 22

Fingerprint

Zinc Oxide
Gallium nitride
Gallium
Epitaxial layers
Zinc oxide
Carrier concentration
Annealing
Carrier transport
Electric potential
Contact resistance
Capacitance
Nitrogen
Doping (additives)
Thin films
Electrons
gallium nitride
Temperature

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

Cite this

Sheu, Jinn-Kong ; Chang, K. H. ; Lee, M. L. ; Huang, J. F. ; Kang, K. S. ; Wang, W. L. ; Lai, Wei-Chi ; Hsueh, T. H. / Characterization of gallium-doped zinc oxide contact on n-type gallium nitride epitaxial layers. In: Journal of the Electrochemical Society. 2009 ; Vol. 156, No. 8.
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Characterization of gallium-doped zinc oxide contact on n-type gallium nitride epitaxial layers. / Sheu, Jinn-Kong; Chang, K. H.; Lee, M. L.; Huang, J. F.; Kang, K. S.; Wang, W. L.; Lai, Wei-Chi; Hsueh, T. H.

In: Journal of the Electrochemical Society, Vol. 156, No. 8, 22.07.2009.

Research output: Contribution to journalArticle

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T1 - Characterization of gallium-doped zinc oxide contact on n-type gallium nitride epitaxial layers

AU - Sheu, Jinn-Kong

AU - Chang, K. H.

AU - Lee, M. L.

AU - Huang, J. F.

AU - Kang, K. S.

AU - Wang, W. L.

AU - Lai, Wei-Chi

AU - Hsueh, T. H.

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N2 - This study demonstrates the electrical characteristics of Ga-doped ZnO (GZO) thin films deposited onto n-type GaN (n-GaN) epitaxial layers with a variety of electron concentrations. The ohmic characteristics could be obtained from the GZO/n-GaN samples after a thermal annealing process was performed at 800°C in a nitrogen atmosphere for 1 min when the n-GaN layers had a carrier concentration of approximately 1× 1019 cm-3. The specific contact resistance (ρ c) was as low as 2.6× 10-4 cm2. The ohmic characteristics can be attributed to the fact that the heavy doping of n-GaN layers and the low resistivity GZO film can result in a carrier transport via a tunneling mechanism at the GZO/GaN interface. However, the GZO/n-GaN samples exhibited nonlinear current-voltage (I-V) characteristics (i.e., a Schottky contact) when the annealing temperature (TA) was lower than or equal to 600°C even though the carrier concentration of n-GaN reached 1× 1019 cm-3. These GZO/n-GaN Schottky contacts were due to the low carrier concentration of GZO films and/or n-GaN layers. The effective Schottky barrier heights of the 700°C annealed GZO/n-GaN (n∼ 1016 cm-3) samples were around 0.73 and 0.75 eV, which were deduced from the I-V and capacitance-voltage characteristics, respectively.

AB - This study demonstrates the electrical characteristics of Ga-doped ZnO (GZO) thin films deposited onto n-type GaN (n-GaN) epitaxial layers with a variety of electron concentrations. The ohmic characteristics could be obtained from the GZO/n-GaN samples after a thermal annealing process was performed at 800°C in a nitrogen atmosphere for 1 min when the n-GaN layers had a carrier concentration of approximately 1× 1019 cm-3. The specific contact resistance (ρ c) was as low as 2.6× 10-4 cm2. The ohmic characteristics can be attributed to the fact that the heavy doping of n-GaN layers and the low resistivity GZO film can result in a carrier transport via a tunneling mechanism at the GZO/GaN interface. However, the GZO/n-GaN samples exhibited nonlinear current-voltage (I-V) characteristics (i.e., a Schottky contact) when the annealing temperature (TA) was lower than or equal to 600°C even though the carrier concentration of n-GaN reached 1× 1019 cm-3. These GZO/n-GaN Schottky contacts were due to the low carrier concentration of GZO films and/or n-GaN layers. The effective Schottky barrier heights of the 700°C annealed GZO/n-GaN (n∼ 1016 cm-3) samples were around 0.73 and 0.75 eV, which were deduced from the I-V and capacitance-voltage characteristics, respectively.

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