Nanoimprinted Hybrid Metal-Semiconductor Plasmonic Multilayers with Controlled Surface Nano Architecture for Applications in NIR Detectors

Abstract

We present a proof of concept for tunable plasmon resonance frequencies in a core shell nano-architectured hybrid metal-semiconductor multilayer structure, with Ag as the active shell and ITO as the dielectric modulation media. Our method relies on the collective change in the dielectric function within the metal semiconductor interface to control the surface. Here we report fabrication and optical spectroscopy studies of large-area, nanostructured, hybrid silver and indium tin oxide (ITO) structures, with feature sizes below 100 nm and a controlled surface architecture. The optical and electrical properties of these core shell electrodes, including the surface plasmon frequency, can be tuned by suitably changing the order and thickness of the dielectric layers. By varying the dimensions of the nanopillars, the surface plasmon wavelength of the nanopillar Ag can be tuned from 650 to 690 nm. Adding layers of ITO to the structure further shifts the resonance wavelength toward the IR region and, depending on the sequence and thickness of the layers within the structure, we show that such structures can be applied in sensing devices including enhancing silicon as a photodetection material.

A rational design of multimodal asymmetric nanoshells as efficient tunable absorbers within the biological optical window

“…On the contrary, when the electric field is parallel to the long axis of the spheroid (PS—Fig. 4 B), surface charges are generated on the tips of the prolate and the situation is reversed and results in a blue-shift of the cavity plasmon mode 54 , 56 .

Figure 4 Surface charge density (Coulomb/m ) plots of shell and core surfaces of ( A ) CS, ( B ) PS and ( C ) OS for bonding mode.

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Enhanced Reflectivity Change and Phase Shift of Polarized Light: Double Parameter Multilayer Sensor

“…Phase-sensitive optical biosensing is of great importance in development of single molecule and low concentration solution studies [2,6,17,18,20] . The SPR approach, where the key parameters are the shift in the wavelength and/or incident angle, is extensively studied [14,17,18,[28][29][30][31][32][33][34] , while change in reflectivity and phase shift is relatively less studied [6,17,18,20] . Some phase sensitive sensor systems are summarized in the Table 1, comparing technologically more challenging sensors with sensors fabricated with the simpler processes.…”

“…Such “fiber” sandwich structure, where , the electric field coupling and enhancement are facilitated. [ 28,29 ] Moreover, a great increase in phase shift can be obtained,thus providing a sensor with two sensitive parameters–reflectivity and phase.…”

“…The optical properties of the Layer 1 are equal with optical properties of the Layer 5, and also the Layer 2 and Layer 4 optical properties are identical, only thickness is different. Such "fiber" sandwich structure, where 𝑁 0 ̃> 𝑁 1 ̃> 𝑁 2 ̃> 𝑁 3 ̃, the electric field coupling and enhancement is facilitated [28,29] . Moreover, a great increase in phase shift can be obtained, thus providing a sensor with two sensitive parameters -reflectivity and phase.…”

“…In the simulations we use the complex dielectric dispersion curves obtained from WOOLLAM RC2 SE investigations for YHO and ZnOx [28] thin films developed at the Thin Film Laboratory of ISSP UL. The fabrication process and characteristics of ZnOx thin films can be found in our reference [35] .…”