Focused Ion Beam (FIB) nanolithography has been employed in the past to fabricate electrical contacts on single nanowires and other one-dimensional (1D) nanomaterials.
In this work, an alternative FIB nanolithography method based on electron beam assisted deposition (EBAD) and ion beam assisted deposition (IBAD) is presented. The Pt- ion and electron beam assisted depositions involve the decomposition C9H16Pt gas molecules, which results in a local deposition of Pt material on the sample in the area where the ion beam is scanned in a predefined pattern. [1-2]. Due to the fact that interaction between electrons and the sample is less destructive than using ions, performing an electron-assisted deposition on the nanostructure to be contacted and finishing the rest of the contact with the help of ions can avoid undesired changes of the nanostructure which are commonly introduced in conventional FIB nanolithography.
According to this technique, a 20 μm long electrochemically synthesized Au nanowire with nominal diameter of 100 nm onto SiO2/Si chips with prepatterned Au/Cr microelectrodes has been electrically contactedThe I–V characteristics of a single Au nanowire were investigated by micro four-point probe set-up. The resistivity of Au nanowires was found to be 2.8 x 10Ω×cm [1]. The formation of 15 nm-sized electrode gaps in Au NWs is achieved by FIB milling. The current-voltage profile of the circuit prior to FIB milling and of the empty gap circuit in air showed ohmic behavior with resistances of ~ 0.55 MΩ and ~ 4 GΩ, respectively [2].
The application of nanoelectrodes, for detection of biomolecules and nanosensor prototypes based on WO3, contacted using this methodology will be presented.
Acknowledgement:
Financial support from the Magnus Bergvall and the Göran Gustafsson Foundations are gratefully acknowledged.
References:
1.S. Valizadeh, M. Abid, M, F. Hernández-Ramírez, A. Romano-Rodríguez, K. Hjort, J.A. Schweitz, Nanotechnology, 17, (2006), 1134-1139.
2.S. Valizadeh, M. Strömberg, K. Welch and M. Strømme, Focused Ion Beam fabrication of electrochemically synthesized nanowire-based electrodes, Physica E: Low- dimensional systems and nanostructures Low Dimensional, Submitted.
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