Electrical properties of sputtered-indium tin oxide film contacts on n-type GaN

J. D. Hwang, C. C. Lin, Wei-Li Chen

Research output: Contribution to journalArticle

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Abstract

A transparent indium tin oxide (ITO) Ohmic contact on n-type gallium nitride (GaN) (dopant concentration of 2 × 10 17 cm -3 ) having a specific contact resistance of 4.2 × 10 -6 Ω cm 2 was obtained. In this study, ITO film deposition method was implemented by sputtering. We found that the barrier height, 0.68 eV, between ITO and n-type GaN is the same for both evaporated- and sputtered-ITO films. However, the 0.68 eV in barrier height renders the evaporated-ITO/n-GaN Schottky contact. This behavior is different from that of our sputtered-ITO/N-GaN, i.e., Ohmic contact. During sputtering, oxygen atoms on the GaN surface were significantly removed, thereby resulting in an improvement in contact resistance. Moreover, a large number of nitrogen (N) vacancies, caused by sputtering, were produced near the GaN surface. These N vacancies acted as donors for electrons, thus affecting a heavily doped n-type formed at the subsurface below the sputtered ITO/n-GaN. Both oxygen removal and heavy doping near the GaN surface, caused by N vacancies, in turn led to a reduction in contact resistivity as a result of electrons tunneling across the depletion layer from the ITO to the n-type GaN. All explanations are given by Auger analysis and x-ray photoelectron spectroscopy.

Original languageEnglish
Article number044908
JournalJournal of Applied Physics
Volume100
Issue number4
DOIs
Publication statusPublished - 2006 Sep 11

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gallium nitrides
indium oxides
tin oxides
oxide films
electrical properties
electric contacts
sputtering
contact resistance
electron tunneling
x ray spectroscopy
oxygen atoms
depletion
photoelectron spectroscopy
nitrogen
electrical resistivity
oxygen

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

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abstract = "A transparent indium tin oxide (ITO) Ohmic contact on n-type gallium nitride (GaN) (dopant concentration of 2 × 10 17 cm -3 ) having a specific contact resistance of 4.2 × 10 -6 Ω cm 2 was obtained. In this study, ITO film deposition method was implemented by sputtering. We found that the barrier height, 0.68 eV, between ITO and n-type GaN is the same for both evaporated- and sputtered-ITO films. However, the 0.68 eV in barrier height renders the evaporated-ITO/n-GaN Schottky contact. This behavior is different from that of our sputtered-ITO/N-GaN, i.e., Ohmic contact. During sputtering, oxygen atoms on the GaN surface were significantly removed, thereby resulting in an improvement in contact resistance. Moreover, a large number of nitrogen (N) vacancies, caused by sputtering, were produced near the GaN surface. These N vacancies acted as donors for electrons, thus affecting a heavily doped n-type formed at the subsurface below the sputtered ITO/n-GaN. Both oxygen removal and heavy doping near the GaN surface, caused by N vacancies, in turn led to a reduction in contact resistivity as a result of electrons tunneling across the depletion layer from the ITO to the n-type GaN. All explanations are given by Auger analysis and x-ray photoelectron spectroscopy.",
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Electrical properties of sputtered-indium tin oxide film contacts on n-type GaN. / Hwang, J. D.; Lin, C. C.; Chen, Wei-Li.

In: Journal of Applied Physics, Vol. 100, No. 4, 044908, 11.09.2006.

Research output: Contribution to journalArticle

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