Ti/Pd/Ag Contacts to n-Type GaAs for High Current Density Devices

Huo, Pengyun and Rey-Stolle Prado, Ignacio (2016). Ti/Pd/Ag Contacts to n-Type GaAs for High Current Density Devices. "Journal of Electronic Materials", v. 45 (n. 6); pp. 2769-2775. ISSN 0361-5235. https://doi.org/10.1007/s11664-016-4432-6.


Title: Ti/Pd/Ag Contacts to n-Type GaAs for High Current Density Devices
  • Huo, Pengyun
  • Rey-Stolle Prado, Ignacio
Item Type: Article
Título de Revista/Publicación: Journal of Electronic Materials
Date: June 2016
ISSN: 0361-5235
Volume: 45
Freetext Keywords: Ohmic contact, n-GaAs, high conductivity
Faculty: Instituto de Energía Solar (IES) (UPM)
Department: Electrónica Física
UPM's Research Group: Semiconductores III-V
Creative Commons Licenses: None

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The metallization stack Ti/Pd/Ag on n-type Si has been readily used in solar cells due to its low metal/semiconductor specific contact resistance, very high sheet conductance, bondability, long-term durability, and cost-effectiveness. In this study, the use of Ti/Pd/Ag metallization on n-type GaAs is examined, targeting electronic devices that need to handle high current densities and with grid-like contacts with limited surface coverage (i.e., solar cells, lasers, or light emitting diodes). Ti/Pd/Ag (50 nm/50 nm/1000 nm) metal layers were deposited on n-type GaAs by electron beam evaporation and the contact quality was assessed for different doping levels (from 1.3 × 1018 cm−3 to 1.6 × 1019 cm−3) and annealing temperatures (from 300°C to 750°C). The metal/semiconductor specific contact resistance, metal resistivity, and the morphology of the contacts were studied. The results show that samples doped in the range of 1018 cm−3 had Schottky-like I–V characteristics and only samples doped 1.6 × 1019 cm−3 exhibited ohmic behavior even before annealing. For the ohmic contacts, increasing annealing temperature causes a decrease in the specific contact resistance (ρ c,Ti/Pd/Ag ~ 5 × 10−4 Ω cm2). In regard to the metal resistivity, Ti/Pd/Ag metallization presents a very good metal conductivity for samples treated below 500°C (ρ M,Ti/Pd/Ag ~ 2.3 × 10−6 Ω cm); however, for samples treated at 750°C, metal resistivity is strongly degraded due to morphological degradation and contamination in the silver overlayer. As compared to the classic AuGe/Ni/Au metal system, the Ti/Pd/Ag system shows higher metal/semiconductor specific contact resistance and one order of magnitude lower metal resistivity.

Funding Projects

Government of SpainTEC2012-37286UnspecifiedIgnacio Rey-StolleFabricación por MOVPE de células solares multiunion de semiconductores III-V sobre silicio

More information

Item ID: 40235
DC Identifier: http://oa.upm.es/40235/
OAI Identifier: oai:oa.upm.es:40235
DOI: 10.1007/s11664-016-4432-6
Official URL: https://link.springer.com/article/10.1007%2Fs11664-016-4432-6
Deposited by: Dr Ignacio Rey-Stolle
Deposited on: 05 May 2016 10:49
Last Modified: 13 Mar 2019 17:27
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