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Low Resistivity n‐type GaN Ohmic Contacts on GaN Substrates

Logotheti, Adamantia LU orcid ; Garigapati, Navya Sri LU ; So, Byeongchan LU orcid ; Colvin, Jovana LU ; Darakchieva, Vanya LU and Lind, Erik LU orcid (2024) In Physica Status Solidi. A: Applications and Materials Science
Abstract
In this study, a report is prepared on significantly low specific contact resistivity of alloyed and non-alloyed ohmic contacts fabricated on an as-grown n+-GaN layer and measured with the transfer length method. A low ρc = 8 × 10−8 Ω cm2 is extracted for the alloyed Ti/Al/Ni/Au, and ρc = 4 × 10−7 Ω cm2 for the unannealed Ti/Pd/Au. To achieve these, a highly doped n+-GaN layer with ND = 1.5 × 1019 cm−3 is used. The results are derived from a study of three different metal contact stacks, namely Ti/Al/Ni/Au (20 nm/300 nm/20 nm/400 nm), Ti/Pd/Au (2 nm/5 nm/200 nm), and Mo/Au (30 nm/200 nm). The Ti/Al/Ni/Au metal contact is studied in both annealed and non-annealed conditions, whereas for the Ti/Pd/Au and Mo/Au ohmic contacts, a study is... (More)
In this study, a report is prepared on significantly low specific contact resistivity of alloyed and non-alloyed ohmic contacts fabricated on an as-grown n+-GaN layer and measured with the transfer length method. A low ρc = 8 × 10−8 Ω cm2 is extracted for the alloyed Ti/Al/Ni/Au, and ρc = 4 × 10−7 Ω cm2 for the unannealed Ti/Pd/Au. To achieve these, a highly doped n+-GaN layer with ND = 1.5 × 1019 cm−3 is used. The results are derived from a study of three different metal contact stacks, namely Ti/Al/Ni/Au (20 nm/300 nm/20 nm/400 nm), Ti/Pd/Au (2 nm/5 nm/200 nm), and Mo/Au (30 nm/200 nm). The Ti/Al/Ni/Au metal contact is studied in both annealed and non-annealed conditions, whereas for the Ti/Pd/Au and Mo/Au ohmic contacts, a study is conducted without annealing. Their performance and thermal stability are evaluated with a four-probe TLM, with temperatures ranging from 25 to 150 °C. Finally, a theoretical model based on thermionic emission theory is employed to gain a deeper understanding of the physical mechanisms governing the behavior of the ohmic contacts. (Less)
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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
epub
subject
keywords
gallium nitride (GaN), contact resistivity, alloyed and non-alloyed
in
Physica Status Solidi. A: Applications and Materials Science
pages
6 pages
publisher
Wiley-VCH Verlag
external identifiers
  • scopus:85209774948
ISSN
1862-6300
DOI
10.1002/pssa.202400692
language
English
LU publication?
yes
id
c227b1c8-3931-4086-bda8-4b48c2e7bd6b
date added to LUP
2024-11-27 16:53:17
date last changed
2025-05-29 18:51:12
@article{c227b1c8-3931-4086-bda8-4b48c2e7bd6b,
  abstract     = {{In this study, a report is prepared on significantly low specific contact resistivity of alloyed and non-alloyed ohmic contacts fabricated on an as-grown n+-GaN layer and measured with the transfer length method. A low ρc = 8 × 10−8 Ω cm2 is extracted for the alloyed Ti/Al/Ni/Au, and ρc = 4 × 10−7 Ω cm2 for the unannealed Ti/Pd/Au. To achieve these, a highly doped n+-GaN layer with ND = 1.5 × 1019 cm−3 is used. The results are derived from a study of three different metal contact stacks, namely Ti/Al/Ni/Au (20 nm/300 nm/20 nm/400 nm), Ti/Pd/Au (2 nm/5 nm/200 nm), and Mo/Au (30 nm/200 nm). The Ti/Al/Ni/Au metal contact is studied in both annealed and non-annealed conditions, whereas for the Ti/Pd/Au and Mo/Au ohmic contacts, a study is conducted without annealing. Their performance and thermal stability are evaluated with a four-probe TLM, with temperatures ranging from 25 to 150 °C. Finally, a theoretical model based on thermionic emission theory is employed to gain a deeper understanding of the physical mechanisms governing the behavior of the ohmic contacts.}},
  author       = {{Logotheti, Adamantia and Garigapati, Navya Sri and So, Byeongchan and Colvin, Jovana and Darakchieva, Vanya and Lind, Erik}},
  issn         = {{1862-6300}},
  keywords     = {{gallium nitride (GaN); contact resistivity; alloyed and non-alloyed}},
  language     = {{eng}},
  month        = {{11}},
  publisher    = {{Wiley-VCH Verlag}},
  series       = {{Physica Status Solidi. A: Applications and Materials Science}},
  title        = {{Low Resistivity n‐type GaN Ohmic Contacts on GaN Substrates}},
  url          = {{http://dx.doi.org/10.1002/pssa.202400692}},
  doi          = {{10.1002/pssa.202400692}},
  year         = {{2024}},
}