Characterization of tungsten-nickel simultaneous Ohmic contacts to p- and n-type 4H-SiC

K. C. Kragh-Buetow, R. S. Okojie, D. Lukco, S. E. Mohney

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Abstract

Ohmic contacts to p- and n-type 4H-SiC using refractory alloyed W:Ni thin films were investigated. Transfer length measurement test structures to p-type 4H-SiC (NA = 3 � 1020 cm-3) revealed Ohmic contacts with specific contact resistances, ρc, of ∼10-5 Ω cm2 after 0.5 h annealing in argon at temperatures of 1000 �C, 1100 �C, 1150 �C, and 1200 �C. Contacts fabricated on n-type 4H-SiC (ND = 2 � 1019 cm-3) by similar methods were shown to have similar specific contact resistance values after annealing, demonstrating simultaneous Ohmic contact formation for W:Ni alloys on 4H-SiC. The lowest ρc values were (7.3 � 0.9) � 10-6 Ω cm2 for p-SiC and (6.8 � 3.1) � 10-6 Ω cm2 for n-SiC after annealing at 1150 �C. X-ray diffraction shows a cubic tungsten-nickel-carbide phase in the Ohmic contacts after annealing as well as WC after higher temperatures. Auger electron spectroscopy depth profiles support the presence of metal carbide regions above a nickel and silicon-rich region near the interface. X-ray energy dispersive spectroscopy mapping showed tungsten-rich and nickel-rich regions after annealing at 1100 �C and above. W:Ni alloys show promise as simultaneous Ohmic contacts to p- and n-SiC, offering low and comparable ρc values along with the formation of WxNiyC.

Original languageEnglish (US)
Article number105019
JournalSemiconductor Science and Technology
Volume30
Issue number10
DOIs
StatePublished - Sep 1 2015

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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