Electrical contacts to nanorod networks at different length scales: From macroscale ensembles to single nanorod chains.

Microelectronic Engineering, 11 April 2013.
Romain Lavieville, Yang Zhang, Enzo Di Fabrizio, Roman Krahne.

Istituto Italiano di Tecnologià, Via Morego 30, 16163 Genova, Italy.

BIONEM Lab, University of Magna Graecia, Campus S. Venuta, viale Europa, 88100 Catanzaro, Italy.

 

 

Abstract

 

The nature of metal–semiconductor interfaces at the nanoscale is an important issue in micro- and nano-electronic engineering. The study of charge transport through chains of CdSe semiconductor nanorods linked by Au particles represents an ideal model system for this matter, because the metal semiconductor interface is an intrinsic feature of the nanosystem. Here we show the controlled fabrication of all-inorganic hybrid metal–semiconductor networks with different size, in which the semiconductor nanorods are linked by Au domains at their tips. We demonstrate different approaches to selectively contact the networks and single nanorod chains with planar electrodes, and we investigate their charge transport at room temperature.

 

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Additional Information

 

Metal-Semiconductor hybrid systems represent an elegant solution to combine the advantageous properties like excellent electrical conduction and plasmon resonances from metals with efficient broad band absorption from semiconductors in one single material. In this respect wet chemical synthesis of networks consisting of CdSe linked by Au nanoparticles via all-inorganic interfaces represent an ideal system for the study of physical properties of such hybrids, where the  nanoscale nature of the metal-semiconductor contact should have an impact, as reported in our recent paper in ACS Nano 6 (4), p 2940. We demonstrated that the nanosize spherical shape of the Au nanoparticles results in a particular reduction of the Schottky barrier formed at the metal semiconductor interface. In the featured article in Microelectronic Engineering we elaborate on different methods how such networks can be electrically contacted on several length scales, from single nanorod chains to large scale network assemblies, and we find that for all size ranges the properties from the nanoscale size of the electrical junctions persist. A complementary system to the nanorod networks consist of CdSe nanowires decorated with Au nanoparticles at their lateral facets, and the photoelectrical properties of such Au-decorated nanowires were reported by us recently (Nanoscale, 2013, DOI: 10.1039/C3NR00752A). Here the metal nanoparticles resulted in a broad-band enhancement of the photocurrent measured on ensembles of such nano wires, which originated from light scattering and from increased electron-hole separation at the metal-semiconductor interface caused by the inherent Schottky fields. Furthermore the Au-decoration created optical hot spots that could be exploited as efficient surface-enhanced Raman spectroscopy (SERS) substrates, demonstrated by chemical mapping of  biomolecules that were functionalized on the hybrid nanowires (Journal of Nanoparticle Research 15, p1596 (2013).

 

Electrical contacts to nanorod networks at different length scales from macroscale ensembles to single nanorod chains

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