Metal-Insulator-Carbon Nanowires for Highly Sensitive, Surface Enhanced Raman Spectroscopy

A.O. Altun, T. Bond, H.G. Park
Lawrence Livermore National Laboratory, US

Keywords: metal, insulator, carbon, nanowire, surface enhanced Raman spectroscopy, femtomolar

Summary:

We report a highly sensitive substrate for surface enhanced Raman spectroscopy (SERS) enabled by arrays of gold coated metallic carbon nanotubes (CNTs) having a high-k dielectric (hafnia, HfO2) nanolayer insert as a potential barrier. Repeated measurements of femtomolar detection of 1,2 bis-(4-pyridyl)-ethylene (BPE) in the solution phase are made even without salient localized plasmon resonantion. Comparison of SERS performance with and without the hafnia insert establishes the critical contribution of this dielectric nano-spacer to the enhanced sensitivity. We attribute this finding to a relief of plasmon leakage in the presence of the virtual potential barrier. Our highly sensitive SERS substrate could find its use in many applications such as biomedical diagnosis, environmental monitoring, and forensic study.