Low resistance ohmic contact on p-type GaN grown by plasma-assisted molecular beam epitaxy

Myung C. Yoo, J. W. Lee, J. M. Myoung, K. H. Shim, K. Kim

Research output: Contribution to journalConference article

6 Citations (Scopus)

Abstract

Ohmic contacts on p-type GaN have been investigated. High quality GaN epilayers on c-plane sapphire were prepared using plasma-assisted molecular beam epitaxy that utilized an inductively coupled rf nitrogen plasma source and solid source beams. The resulting film thickness and the doping concentration of the grown samples were in the range of 0.7-1.35 μm and 1018-1020/cm3 respectively. The metallization consisted of high work function metal bi-layers which included a combinations of 25 nm-thick Ni, Ti, Pt and/or Cr and 200 nm-thick Au on the highly p-doped GaN in a transmission line model pattern. Ohmic contacts were formed by alloying the bi-layers using rapid thermal annealing (RTA) at temperatures in the range of 300-700 °C for 1 min under nitrogen ambient. Current-voltage measurements showed that the specific contact resistance was as low as 1.2×10-4 Ω-cm2 for the sample having 1.4×1020/cm3 p-type doping concentration with a Cr/Au contact annealed at 500 °C for 1 min by RTA. Judging from the scanning Auger microscopy results and the glancing angle x-ray diffraction analysis, this resistance is attributed to Cr diffusion into the GaN layer.

Original languageEnglish
Pages (from-to)131-136
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume423
Publication statusPublished - 1996 Dec 1
EventProceedings of the 1996 MRS Spring Symposium - San Francisco, CA, USA
Duration: 1996 Apr 81996 Apr 12

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Ohmic contacts
Rapid thermal annealing
low resistance
Molecular beam epitaxy
electric contacts
molecular beam epitaxy
Doping (additives)
Nitrogen plasma
Plasmas
Plasma sources
Aluminum Oxide
Epilayers
Voltage measurement
Inductively coupled plasma
Electric current measurement
Contact resistance
Metallizing
Alloying
Sapphire
Film thickness

All Science Journal Classification (ASJC) codes

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

Cite this

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title = "Low resistance ohmic contact on p-type GaN grown by plasma-assisted molecular beam epitaxy",
abstract = "Ohmic contacts on p-type GaN have been investigated. High quality GaN epilayers on c-plane sapphire were prepared using plasma-assisted molecular beam epitaxy that utilized an inductively coupled rf nitrogen plasma source and solid source beams. The resulting film thickness and the doping concentration of the grown samples were in the range of 0.7-1.35 μm and 1018-1020/cm3 respectively. The metallization consisted of high work function metal bi-layers which included a combinations of 25 nm-thick Ni, Ti, Pt and/or Cr and 200 nm-thick Au on the highly p-doped GaN in a transmission line model pattern. Ohmic contacts were formed by alloying the bi-layers using rapid thermal annealing (RTA) at temperatures in the range of 300-700 °C for 1 min under nitrogen ambient. Current-voltage measurements showed that the specific contact resistance was as low as 1.2×10-4 Ω-cm2 for the sample having 1.4×1020/cm3 p-type doping concentration with a Cr/Au contact annealed at 500 °C for 1 min by RTA. Judging from the scanning Auger microscopy results and the glancing angle x-ray diffraction analysis, this resistance is attributed to Cr diffusion into the GaN layer.",
author = "Yoo, {Myung C.} and Lee, {J. W.} and Myoung, {J. M.} and Shim, {K. H.} and K. Kim",
year = "1996",
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Low resistance ohmic contact on p-type GaN grown by plasma-assisted molecular beam epitaxy. / Yoo, Myung C.; Lee, J. W.; Myoung, J. M.; Shim, K. H.; Kim, K.

In: Materials Research Society Symposium - Proceedings, Vol. 423, 01.12.1996, p. 131-136.

Research output: Contribution to journalConference article

TY - JOUR

T1 - Low resistance ohmic contact on p-type GaN grown by plasma-assisted molecular beam epitaxy

AU - Yoo, Myung C.

AU - Lee, J. W.

AU - Myoung, J. M.

AU - Shim, K. H.

AU - Kim, K.

PY - 1996/12/1

Y1 - 1996/12/1

N2 - Ohmic contacts on p-type GaN have been investigated. High quality GaN epilayers on c-plane sapphire were prepared using plasma-assisted molecular beam epitaxy that utilized an inductively coupled rf nitrogen plasma source and solid source beams. The resulting film thickness and the doping concentration of the grown samples were in the range of 0.7-1.35 μm and 1018-1020/cm3 respectively. The metallization consisted of high work function metal bi-layers which included a combinations of 25 nm-thick Ni, Ti, Pt and/or Cr and 200 nm-thick Au on the highly p-doped GaN in a transmission line model pattern. Ohmic contacts were formed by alloying the bi-layers using rapid thermal annealing (RTA) at temperatures in the range of 300-700 °C for 1 min under nitrogen ambient. Current-voltage measurements showed that the specific contact resistance was as low as 1.2×10-4 Ω-cm2 for the sample having 1.4×1020/cm3 p-type doping concentration with a Cr/Au contact annealed at 500 °C for 1 min by RTA. Judging from the scanning Auger microscopy results and the glancing angle x-ray diffraction analysis, this resistance is attributed to Cr diffusion into the GaN layer.

AB - Ohmic contacts on p-type GaN have been investigated. High quality GaN epilayers on c-plane sapphire were prepared using plasma-assisted molecular beam epitaxy that utilized an inductively coupled rf nitrogen plasma source and solid source beams. The resulting film thickness and the doping concentration of the grown samples were in the range of 0.7-1.35 μm and 1018-1020/cm3 respectively. The metallization consisted of high work function metal bi-layers which included a combinations of 25 nm-thick Ni, Ti, Pt and/or Cr and 200 nm-thick Au on the highly p-doped GaN in a transmission line model pattern. Ohmic contacts were formed by alloying the bi-layers using rapid thermal annealing (RTA) at temperatures in the range of 300-700 °C for 1 min under nitrogen ambient. Current-voltage measurements showed that the specific contact resistance was as low as 1.2×10-4 Ω-cm2 for the sample having 1.4×1020/cm3 p-type doping concentration with a Cr/Au contact annealed at 500 °C for 1 min by RTA. Judging from the scanning Auger microscopy results and the glancing angle x-ray diffraction analysis, this resistance is attributed to Cr diffusion into the GaN layer.

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