Stable Pt/Ge/Au ohmic contact to n-GaAs with a Ta-Si-N barrier

J. S. Chen, E. Kolawa, R. P. Ruiz, M. A. Nicolet

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

A Pt/Ge/Au contact of the structure: 〈n- GaAs〉/Pt(17 nm)/Ge(25 nm)/Au(43 nm), overlaid with a Ta-Si-N barrier layer and a Au metallization layer has a contact resistivity, ρc, of 3.7×10-6 Ωcm2 after annealing at 450 °C for 15 min. After aging at 450 °C for 60 h, ρc slightly degrades to 5.5×10-6 Ωcm2 while the surface keeps smooth. When alloyed at 550 °C for 15 min, ρc is 1.8×10-6 Ωcm2 and stays about the same value after annealing at 550 °C for 1 h. Without the Ta-Si-N barrier and the Au overlayer, the Pt/Ge/Au contact alone is also ohmic after annealing at 450 °C for 15 min but with a ρc of approximately 10-5 Ωcm2 while the surface morphology deteriorates significantly after aging at 450 °C for 20 h. The thermal reactions of this Pt/Ge/Au contact on GaAs, with or without a Ta-Si-N barrier layer, are investigated by backscattering spectrometry, x-ray diffraction, and transmission electron microscopy in conjunction with energy dispersive analyses of x-rays. For all samples, the main reaction products after annealing at 450 °C for 15 min are Au7Ga2 and PtGe:As, a PtGe phase that also contains arsenic. The product phases are randomly distributed within a laterally uniform reacted layer when the Pt/Ge/Au contact is covered by a Ta-Si-N layer. Without the Ta-Si-N barrier layer, a small arsenic loss and a Ga-rich phase (probably Ga-oxides) on the contact surface are observed after annealing at 450 °C. In this case, the surface and contact-semiconductor interface are more faceted than with a Ta-Si-N barrier layer.

Original languageEnglish
Title of host publicationIII-V Electronic and Photonic Device Fabrication and Performance
PublisherPubl by Materials Research Society
Pages255-260
Number of pages6
ISBN (Print)1558991964, 9781558991965
DOIs
Publication statusPublished - 1993
EventMaterials Research Society Spring Meeting - San Francisco, CA, USA
Duration: 1993 Apr 121993 Apr 15

Publication series

NameMaterials Research Society Symposium Proceedings
Volume300
ISSN (Print)0272-9172

Other

OtherMaterials Research Society Spring Meeting
CitySan Francisco, CA, USA
Period93-04-1293-04-15

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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  • Cite this

    Chen, J. S., Kolawa, E., Ruiz, R. P., & Nicolet, M. A. (1993). Stable Pt/Ge/Au ohmic contact to n-GaAs with a Ta-Si-N barrier. In III-V Electronic and Photonic Device Fabrication and Performance (pp. 255-260). (Materials Research Society Symposium Proceedings; Vol. 300). Publ by Materials Research Society. https://doi.org/10.1557/proc-300-255