title: Controllable doping and wrap-around contacts to electrolessly etched silicon nanowire arrays.
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 (10(17)-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 (∼10(20) 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 cm(2)) 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.
authors.affiliation: Department of Mechanical Engineering, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA.
authors.forename: Jyothi S
authors.initials: JS
authors.lastname: Sadhu
authors.forename: Hongxiang
authors.initials: H
authors.lastname: Tian
authors.forename: Timothy
authors.initials: T
authors.lastname: Spila
authors.forename: Junhwan
authors.initials: J
authors.lastname: Kim
authors.forename: Bruno
authors.initials: B
authors.lastname: Azeredo
authors.forename: Placid
authors.initials: P
authors.lastname: Ferreira
authors.forename: Sanjiv
authors.initials: S
authors.lastname: Sinha