Journal of Materials Science

, Volume 29, Issue 16, pp 4238–4243 | Cite as

The effects of Ge content on the microstructure and specific contact resistance of solid-state NiAuGe/ZrB2/Au ohmic contacts to n-InGaAs

  • J. S. Yu
  • A. E. Staton-Bevan
  • J. Herniman
  • D. A. Allan


The Ge thickness, x, of NiAuGe(5 nm/45 nm/xnm)/ZrB2(50 nm)/Au(20 nm) ohmic contacts to n-lnGaAs was varied between 0 and 20 nm. The microstructures of these contacts, after annealing at 270°C, were investigated using transmission electron microscopy (TEM) and correlated with the respective specific contact resistances. In the absence of Ge, a Ni-Ga-As phase was formed at the metal-semiconductor interface and the specific contact resistance was high (0.63 Ωmm). When thicknesses of x = 10 nm or x = 15 nm of Ge were added, Ni-Ge-As phases were observed, but they were replaced by AuGeAs and NiGe when x = 20 nm. The specific contact resistance was a minimum (0.11 Ωmm) for this composition. Ge was clearly beneficial for ohmic-contact formation. The low-temperature I–V characteristics of the contact containing the largest amount of Ge (that is, x = 20 nm) indicated that electron tunnelling through degenerately-Ge-doped regions was not the dominant ohmic mechanism in these contacts.


Polymer Microstructure Microscopy Electron Microscopy Transmission Electron Microscopy 
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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • J. S. Yu
    • 1
  • A. E. Staton-Bevan
    • 1
  • J. Herniman
    • 2
  • D. A. Allan
    • 2
  1. 1.Department of Materials, Imperial College of Science, Technology and MedicineUniversity of LondonLondonUK
  2. 2.British Telecom LaboratoriesMartlesham HeathIpswichUK

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