Development of surface-enhanced Raman spectroscopy using optical lens with deposited Ag thin film

At a Glance

Metadata	Details
Publication Date	2016-01-01
Journal	The Proceedings of Mechanical Engineering Congress Japan
Authors	Yamato SASANO, Hiroshi TANI, Renguo Lü, Shinji Koganezawa, Norio TAGAWA
Institutions	Kansai University
Analysis	Full AI Review Included

Technical Documentation and Analysis: Plasmonic SERS Enhancement

This document analyzes the research paper J1610301, “Development of surface-enhanced Raman spectroscopy using optical lens with deposited Ag thin film,” focusing on the material science requirements and connecting them directly to 6CCVD’s advanced MPCVD diamond capabilities.

Executive Summary

The research successfully developed a high-sensitivity analytical method for ultra-thin films using a novel plasmonic lens, achieving significant signal enhancement for surface analysis.

Core Challenge: Analyzing the chemical structure of ultra-thin (few nm) Diamond-Like Carbon (DLC) protective films on Hard Disk Drives (HDDs) using standard, low-output Raman spectroscopy was difficult.
Solution: A “plasmonic lens” was created by depositing an island-like Ag thin film onto a plano-convex lens to leverage Surface-Enhanced Raman Scattering (SERS).
Mechanism: Localized Surface Plasmon Resonance (LSPR) generated by the Ag nanoparticles dramatically amplified the weak Raman signal from the DLC layer.
Key Achievement: The developed plasmonic lens achieved a Raman signal enhancement of 100 times or more for the DLC G-band peak (1570 cm^-1) compared to non-SERS measurements.
Engineering Innovation: A custom lens holding jig was designed to mount the plasmonic lens onto a standard Raman microscope, ensuring precise XY positioning and preventing the fragile Ag film from peeling during contact measurement.
Future Impact: This technique provides a powerful, effective analytical method for detailed surface structure analysis of protective films where signal output is traditionally low.

Technical Specifications

The following hard data points were extracted from the research detailing the experimental parameters and performance metrics.

Parameter	Value	Unit	Context
Target Film Material	DLC (Diamond Like Carbon)	N/A	Protective layer on HDD
Target Film Thickness	Few	nm	Thickness making standard Raman difficult
Target Raman Peak	1570	cm^-1	G-band peak used for intensity evaluation
Signal Enhancement Factor	100+	Times	Compared to standard DLC Raman measurement
Plasmonic Material	Ag	N/A	Deposited via evaporation
Ag Mass Tested (Example 1)	0.01	g	Used for evaporation onto lens surface
Ag Mass Tested (Example 2)	0.03	g	Used for evaporation onto lens surface
Surface Preparation	Fluorocarbon	N/A	Coating used to promote island formation

Key Methodologies

The experiment focused on controlling the surface morphology of the metal film to maximize plasmonic enhancement.

Substrate Selection: A spherical plano-convex lens was chosen as the substrate for the plasmonic sensor, allowing laser irradiation from the flat side while the convex, metalized side contacts the sample.
Surface Energy Control: A fluorocarbon coating was applied to the lens surface prior to metalization. This step was critical to lower the surface energy, encouraging the evaporated metal (Ag) to form the necessary island-like (nanoparticle) structures required for LSPR.
Metalization Process: Ag thin films were deposited onto the prepared lens surface using a controlled evaporation method. The mass of the evaporated Ag was varied (e.g., 0.01g and 0.03g) to investigate the optimal density for maximum Raman signal enhancement.
SERS Measurement: The Ag-coated lens was brought into direct contact with the DLC film on the magnetic disk. Raman scattering analysis was performed by irradiating the contact area with a laser.
Mechanical Stabilization: A custom lens holding jig was designed and implemented. This jig mounts directly onto a standard Raman microscope objective, featuring a spring-loaded mechanism to allow precise XY positioning and prevent the fragile evaporated Ag film from peeling during continuous measurement.

6CCVD Solutions & Capabilities

The development of high-performance plasmonic sensors requires substrates with exceptional optical clarity, thermal stability, and precise metalization capabilities. While the paper utilized a standard glass lens, 6CCVD’s MPCVD diamond materials offer superior performance for replicating and advancing this SERS technology, especially in high-power laser environments.

Applicable Materials

6CCVD recommends the following materials for next-generation plasmonic SERS substrates:

6CCVD Material	Application Advantage	Key Specification
Optical Grade Single Crystal Diamond (SCD)	Ideal for high-power laser applications (Raman). Diamond’s high thermal conductivity (up to 2200 W/mK) prevents thermal drift and damage, ensuring stable plasmonic performance.	Polishing available down to Ra < 1 nm, providing an ultra-smooth foundation for controlled nanoparticle growth.
Polycrystalline Diamond (PCD)	Cost-effective substrate for larger area plasmonic arrays or sensors (e.g., inch-size wafers). Excellent mechanical and thermal stability.	Available in large plates/wafers up to 125mm diameter.
Boron-Doped Diamond (BDD)	Suitable for electrochemical SERS (EC-SERS) applications where the plasmonic substrate also requires electrical conductivity for biasing or sensing.	Can be supplied with varying doping levels for specific conductivity requirements.

Customization Potential

The success of the plasmonic lens hinges on precise geometry and controlled thin-film deposition—core competencies of 6CCVD.

Precision Metalization Services: While the paper used Ag, 6CCVD offers in-house deposition of standard plasmonic and adhesion layers, including Au, Pt, Pd, Ti, W, and Cu. We can engineer custom multi-layer stacks (e.g., Ti/Au) optimized for specific LSPR wavelengths and adhesion to diamond surfaces.
Custom Dimensions and Geometry: 6CCVD can supply SCD or PCD substrates in custom shapes and dimensions required for specialized optical components, including laser cutting services to match the exact geometry (e.g., plano-convex or wedge shapes) needed for integration into existing Raman microscope objectives.
Surface Engineering for Film Morphology: The research highlighted the need for surface energy control (via fluorocarbon coating) to achieve island-like Ag structures. 6CCVD’s expertise in diamond surface termination (e.g., H-termination, O-termination) allows for precise control over the initial surface energy, enabling researchers to optimize the growth of plasmonic nanoparticles directly on the diamond substrate.

Engineering Support

6CCVD’s in-house team of PhD material scientists is available to consult on the integration of diamond into advanced analytical systems. We offer support in:

Material selection to optimize thermal management and optical transparency for specific laser wavelengths.
Designing metalization recipes to achieve desired film thickness (0.1 µm to 500 µm) and morphology for maximum plasmonic enhancement.
Providing global shipping (DDU default, DDP available) for custom diamond components worldwide.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

In recent years, the information society rapidly developed. It is required to increase density of hard disk drives (HDDs). In order to achieve the high density HDDs, details of magnetic disk surface have to been studied to understand the some properties related with the head-disk interface. However, it has become difficult to analyze chemical structure of diamond like carbon (DLC) surface using Raman spectroscopy, because DLC film became much thin. In this study, we made the plasmonic lens for the surface-enhanced Raman spectroscopy. And we measured Raman spectrum of DLC using our developed plasmonic lens.

Tech Support

Original Source

DOI: https://doi.org/10.1299/jsmemecj.2016.j1610301