Kinetics of Ni/a-Ge bilayer reactions

J. Ken Patterson, B. J. Park, K. Ritley, H. Z. Xiao, L. H. Allen, A. Rockett

Research output: Contribution to journalArticlepeer-review


Thin film reactions between 100 nm of Ni and 400 nm of Ge deposited on thermally oxidized Si wafers have been studied as a function of annealing conditions, using X-ray diffraction (XRD), cross-sectional transmission electron microscopy, four-point kelvin resistance measurements and X-ray photoelectron spectroscopy (XPS); these last two techniques were carried out during reaction. The real-time resistance characteristic was nearly identical for temperature ramp rates between 3 and 50°C min-1 over the temperature range 20-550 °C, suggesting that the same basic reactions path dominates for all these conditions. The initial room temperature sheet resistance of the bilayer structure is about ∼ 2 Ω/□ and, upon annealing, goes through a local maximum of ∼ 6 Ω/□ at 300 °C. XPS indicates that Ge first appears on the sample surface, while XRD indicates the presence of monoclinic Ni5Ge3 at this sheet resistance maximum. Orthorhombic NiGe nucleates and grows between 300 and 400 °C. Analysis of resistance vs. time during isothermal annealings at 200-300 °C suggests the formation of NiGe through a thermally activated process with activation energy Ea = 1.3 eV. At temperatures approaching 500 °C, XPS shows the disppearance of the Ni signal from the surface, indicating the onset agglomeration.

Original languageEnglish (US)
Pages (from-to)456-461
Number of pages6
JournalThin Solid Films
Issue number1-2
StatePublished - Dec 15 1994
Externally publishedYes


  • Alloys
  • Germanium
  • Nickel
  • Reaction kinetics

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Condensed Matter Physics
  • Surfaces and Interfaces


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