Surface-Enhanced Raman Scattering Transparent Devices Based on Nanocone Forests
ZHAO Qian1,2, YANG Yu-dong1, GUI Bo1,2, MAO Hai-yang1,2,3*, LI Rui-rui1, CHEN Da-peng1,2,3
1. Integrated Circuit Advanced Process R&D Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. Wuxi IoT Innovation Center Co., Ltd., Wuxi 214135, China
Abstract：Surface-enhanced Raman scattering(SERS) devices with advantages of being non-destructive, ultra-sensitive, and real-time are of significance. For now, most SERS devices are constructed on non-transparent substrates. When such non-transparent SERS devices are used to detect analytes with high concentrations, laser can only be incident from their front-sides. It means that incident laser needs to penetrate analyte molecules to reach metallic nanostructures at the bottom, so laser energy used to excite surface plasmon resonance (SPR) of metallic nanostructures is attenuated, and accordingly, SERS spectral signals are also attenuated; besides, SERS spectral signals cannot be efficiently returned to the charge-coupled device(CCD) due to the blocking of analyte molecules, so that the signals are greatly reduced and in some cases, they cannot be detected at all. In contrast, when a transparent SERS device is adopted, the analyte molecules are placed on front-side of the device and Raman laser is incident from the back-side. In this way, analyte molecules with high concentration have minimal influence on incident laser and SERS spectral signals, so better spectral signals can be obtained. In this work, a polyimide(PI) layer was spin-coated on a quartz substrate, and then the substrate was bombarded by oxygen plasma without masks. After that, nanofiber masks were formed on the quartz substrate. Later on, quartz nanocone forests were formed by a reactive-ion-etching (RIE) step. Subsequently, metallic nanoparticles were sputtered on the nanocones, thus, a transparent SERS device was obtained. For this SERS transparent device, Raman laser can be incident from front-side and back-side of the device during the test. The preliminary experimental results showed that for Rhodamine 6G (R6G), in a concentration range of 10-3～10-6 mol·L-1, the SERS spectra from the back-side were with higher intensities than those from the front-side. In addition, repeatability of the device detected from the back-side was further studied. These results demonstrated the feasibility of the device in practical biochemical detection applications. This work is expected to extend the applications of SERS technique in the field of analyte detections.
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