Hafnium-doped zinc oxide (HZO) has been recently demonstrated to be implemented as a transparent conducting oxide (TCO) material in photovoltaic applications but its plasmonic properties are left untouched. In this work, we systematically investigate the plasmonic properties of gold nanoparticle (Au NP) arrays on thin HZO film, for different ratios of Hf dopants to Zinc oxide (ZnO) film. A localized surface plasmon resonant (LSPR) mode and two Bragg modes (due to the coupling of plasmon modes inside the film to array periodicity) are observed in the proposed structure. Resonant excitation of these modes produces large field enhancement at the surface of the NPs as well as Au NP/HZO film interface and was observed with FDTD simulations. The optimized plasmonic structure will be fabricated on quartz crystal microbalance (QCM) using laser interference lithography, based on the plasmonic resonant position and the SERS (surface enhanced Raman scattering) intensity, and it will be integrated to a microfluidic device in the configuration of the lab-on-a-chip concept for biosensing applications.
Recent years have seen a rapid progress in the field of surface-enhanced Raman spectroscopy (SERS) which is attributed to the thriving field of plasmonics . SERS is a susceptible technique that can address basic scientific questions and technological problems. In both cases, it is highly dependent upon the plasmonic substrate, where excitation of the localized surface plasmon resonance enhances the vibrational scattering signal of the analyte molecules adsorbed on to the surface . In this work, using finite difference time domain (FDTD) method we investigate the optical properties of plasmonic nanostructures with tuned plasmonic resonances as a function of dielectric environment and geometric parameters. An optimized geometry will be discussed based on the plasmonic resonant position and the SERS intensity. These SERS substrates will be employed for the detection of changes in conformation caused by interactions between an aptamer and analyte molecules. This will be done by using a microfluidic channel designed within the configuration of the lab-on-a-chip concept based on the intensity changes of the SERS signal. More efficient and reproducible results are obtained for such a quantitative measurement of analytes at low concentration levels. We will also demonstrate that the plasmonic substrates fabricated by top down approach such as e-beam lithography (EBL) and laser interference lithography (LIL) are highly reproducible, robust and can result in high electric field enhancement. Our results demonstrate the potential to use SERS substrates for highly sensitive detection schemes opening up the window for a wide range of applications including biomedical diagnostics, forensic investigation etc.
This work was supported by the Austrian Science Fund (FWF), project NANOBIOSENSOR (I 2647).
 J. N. Anker, W. P. Hall, O. Lyandres, N. C. Shah, J. Zhao and R. P. V. Duyne., " Biosensing with plasmonic nanosensors," Nature materials, 308(7), 2008.
 T. Y. Jeon1, D. J. Kim, S. Park, S. Kim and D. Kim., "Nanostructured plasmonic substrates for use as SERS sensors," Nanocovergence, 3(18), 2016.
In this work, we explore the sensing applications of Surface Plasmon Resonance (SPR) enhanced
transmission of light through 1-D metal gratings on commonly available compact discs (CDs). We show that SPR
on CDs (CD-SPR) can be used to build a simple and compact angular displacement measurement system with submicro-
radian resolution. In addition we show that by controlling the azimuthal angle of the grating vector with
respect to incident k-vector, it is also possible to measure angular displacement in two planes which is not possible
with thin film SPR. The major advantage of this method is the compact form factor which will enable CD-SPR
based angular measurement systems to be integrated into other experimental setups with the least burden.