Research on preparation SERS substrates of Silver nano-island by sputtering deposition

Hung-Chun Lin^1*, Jin-Cherng Hsu^1,2, Chi-Shun Tu¹, Ting-Yu Liu³, Guan-Yi Hung⁴, Yueh-Sheng Chiang²

¹Department of Physics, Fu Jen Catholic University, New Taipei, Taiwan
²Ph.D. Graduate Institute of Applied Science and Engineering, Fu Jen Catholic University, New Taipei, Taiwan
³Department of Materials Engineering, Ming Chi University of Technology, New Taipei, Taiwan
⁴International P.h.D program in innovative technology of biomedical Engineering and Medical devices, Ming Chi Univeersity of technology, New Taipei, Taiwan

* Presenter:Hung-Chun Lin, email:gguf123tw12345@gmail.com

In the past, when conducting Raman spectroscopy detection of drugs and poisons, the spectral intensity gain was not good, or the concentration of the detection solution was too low, which made detection difficult. This study used a vacuum sputtering physical vapor deposition method to produce silver films of different nanometer sizes as a substrate for enhancing Raman signals.
The process has the characteristics of low cost, high stable deposition rate, and high mass production rate. The silver films with different nanometer thicknesses were deposited on substrates with a fixed DC voltage of 1000 V, fixed DC current of 0.01 A, and various coating times during the research. The island-like of silver particle distribution was observed with an electron microscope (SEM). Moreover, exploring the enhanced Raman signal changes produced by different silver film thicknesses evenly coated Rhodamine 6G as the tested object is studied. It showed that the quartz-monitored Ag-4 sample with a silver film thickness of 4 nm performed the best Raman enhancement when irradiated at different wavelengths. Rhodamine 6G concentration detection reaching the limit of <10^-9 M shows its high sensitivity.
A 632.8 nm, 0.2mW He-Ne laser irradiates three randomly selected samples in three places. The error of the detected Raman intensity within 2.76% shows its good reproducibility. This silver-deposited substrate was placed in a simple air-exhausted moisture-proof box for ten weeks and then coated with Rhodamine 6G for the Raman scattering experiment. No spectrum attenuation phenomenon shows its high stability. Furthermore, the SERS enhancement factor is up to 2.42×10 9. Combining the above advantages, the Ag-deposited SERS chip produced by this research has a high potential in detecting drugs and poisons.

Keywords: surface-enhanced Raman scattering (SERS), silver film , sputtering , detection of drugs and poisons