title: Controlling the Electrical Transport Properties of Nanocontacts to Nanowires.
abstract: The ability to control the properties of electrical contacts to nanostructures is essential to realize operational nanodevices. Here, we show that the electrical behavior of the nanocontacts between free-standing ZnO nanowires and the catalytic Au particle used for their growth can switch from Schottky to Ohmic depending on the size of the Au particles in relation to the cross-sectional width of the ZnO nanowires. We observe a distinct Schottky to Ohmic transition in transport behavior at an Au to nanowire diameter ratio of 0.6. The current-voltage electrical measurements performed with a multiprobe instrument are explained using 3-D self-consistent electrostatic and transport simulations revealing that tunneling at the contact edge is the dominant carrier transport mechanism for these nanoscale contacts. The results are applicable to other nanowire materials such as Si, GaAs, and InAs when the effects of surface charge and contact size are considered.
authors.forename: Alex M
authors.initials: AM
authors.lastname: Lord
authors.forename: Thierry G
authors.initials: TG
authors.lastname: Maffeis
authors.forename: Olga
authors.initials: O
authors.lastname: Kryvchenkova
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cobley
authors.forename: Karol
authors.initials: K
authors.lastname: Kalna
authors.affiliation: ⊥SuperSTEM Laboratory, SFTC Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, United Kingdom.
authors.forename: Despoina M
authors.initials: DM
authors.lastname: Kepaptsoglou
authors.affiliation: ⊥SuperSTEM Laboratory, SFTC Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, United Kingdom.
authors.forename: Quentin M
authors.initials: QM
authors.lastname: Ramasse
authors.forename: Alex S
authors.initials: AS
authors.lastname: Walton
authors.forename: Michael B
authors.initials: MB
authors.lastname: Ward
authors.forename: Jürgen
authors.initials: J
authors.lastname: Köble
authors.forename: Steve P
authors.initials: SP
authors.lastname: Wilks
keywords: Electrical contacts; Ohmic; Schottky; edge effect; nanowires; tunneling