The laser 532 nm can penetrates around 700 nm depth in the sample, ( in the case, silicon cabide 4H) so then, the nickel silicide films we fabricated have around 150 nm thick. When we perform raman tests we can see only silicon carbide peaks. How to solve the depth problem of laser penetration ?
Dear friend Renato Beraldo
Alright, buckle up because I am here to tackle the Raman spectroscopy challenge with unbridled enthusiasm!
Now, about your dilemma with those elusive nickel silicide peaks buried beneath the dominating silicon carbide signals—this is a classic battle of penetration depth, and we're going to conquer it!
1. **Adjust Laser Wavelength:**
- Try using a laser with a longer wavelength. Longer wavelengths generally penetrate deeper into materials. Consider a laser in the near-infrared range, which may better interact with the nickel silicide layer.
2. **Utilize Multiple Excitation Wavelengths:**
- Employ different laser wavelengths to selectively excite different materials. This multi-wavelength approach can help unveil the distinct Raman signatures of both silicon carbide and nickel silicide.
3. **Optimize Laser Power:**
- Adjust the laser power. Lower power might reduce the depth of penetration, potentially allowing you to focus on the thinner nickel silicide layer.
4. **Confocal Raman Microscopy:**
- If available, consider using confocal Raman microscopy. This technique uses a pinhole to eliminate out-of-focus light, enabling better depth resolution.
5. **Enhance Signal from Nickel Silicide:**
- Experiment with enhancing techniques. Surface-enhanced Raman spectroscopy (SERS) or resonance Raman scattering might amplify the nickel silicide signals.
6. **Thin Sectioning:**
- If feasible, consider thin sectioning your sample. Reducing the thickness of your sample can improve the chances of detecting the nickel silicide peaks.
7. **Sample Preparation:**
- Optimize sample preparation. Ensure a smooth and uniform surface. Any irregularities might affect the depth of focus.
8. **Collaborate and Seek Expert Advice:**
- Don't hesitate to reach out to Raman spectroscopy experts or collaborate with researchers who specialize in similar materials. Their experience could provide valuable insights.
Now, go forth, fearless experimenter Renato Beraldo! Conquer the depth problem and unveil the mysteries hidden within those nickel silicide thin films. I believe in you!
Dear Kaushik Shandilya
Thank you so much for such amazing feedback!
I was trying to find some information from papers with related issue and got some stuff so far.
1 - Use Short focus offset. (It increases the surface area analyses)
2 - Laser incidence from the opposite side and focused on the interface region (SiC/NixSiy) through the SiC substrate. (Since SiC is highly transparent for visible lasers because of its wide-band gap nature.
About some of your advice,
1/2 - Unfortunately I have only 325 nm and 532 nm (outside of my campus)
3 - That is a good issue and I'm gonna check
( But, some NixSiCy peaks require 100% powered laser to show a tinny peak =( - Maybe I can check at the interest region range - )
4 - I'm gonna try that
5 - We cannot provide such resource (financial issues)
6 - I'm gonna try that also!!!
7 / 8 - Underway!
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