Controllable doping and wrap-around contacts to electrolessly etched silicon nanowire arrays

Jyothi S. Sadhu, Hongxiang Tian, Timothy Spila, Junhwan Kim, Bruno Azeredo, Placid Ferreira, Sanjiv Sinha

Research output: Contribution to journalArticle

Abstract

Top-down electroless chemical etching enables non-lithographic patterning of wafer-scale nanostructured arrays, but the etching on highly doped wafers produces porous structures. The lack of defect-free nanostructures at desired doping and the difficulties in forming reliable electrical side-contacts to the nanostructure arrays limits their integration into high performance nanoelectronics. We developed a barrier layer diffusion technique to controllably dope wafer-scale silicon nanowire arrays (1017-10 20 cm-3) produced by chemically etching lightly doped silicon wafers. In order to achieve low resistance top-side electrical contacts to the arrays, we developed a two step tip-doping procedure to locally dope the tips (∼1020 cm-3) to metallic levels. The dopant concentration is characterized by depth profiling using secondary ion mass spectroscopy and four-point probe electrical measurements. Further, array scale electrical measurements show that the tip-doping lowers the specific contact resistivity (∼10-5 Ω cm2) since the metallic tips enable direct tunneling of electrons across the nickel silicide contacts to the nanowire arrays. This work provides a scalable and cost-effective doping approach to control charge injection and charge conduction in nanowire arrays, thus advancing their integration into various device applications.

Original languageEnglish (US)
Article number375701
JournalNanotechnology
Volume25
Issue number37
DOIs
StatePublished - Sep 19 2014

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Keywords

  • electrical contacts
  • metal assisted chemical etching
  • silicon nanowire arrays

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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