Interference-enhanced deep-ultraviolet Raman signals of hexagonal boron nitride flake and its underlying silicon substrate

We take hexagonal boron nitride (hBN) flakes exfoliated on SiO 2/Si substrates as a prototype, to demonstrate how to enhance the Raman signals both from ultra-thin layered materials and the underlying opaque substrate excited by deep ultraviolet (DUV) laser. We found that the interference effect in the hBN/SiO 2/Si multilayered structure can largely enhance Raman intensity of hBN flake and the underlying Si substrate under 266-nm excitation. This enhancement effect is more significant than that under visible excitation. With increasing the thickness of SiO 2 layer in the substrate, the corresponding hBN and Si Raman intensity can vary by up to similar to 4 and similar to 2 orders of magnitude under 266-nm excitation, respectively. This method can be applicable to enhance Raman signal from other two-dimensional materials under DUV excitation by tuning the thickness of SiO 2 layer in the SiO 2/Si substrate.

Automated summary

By adjusting the thickness of the SiO 2 layer in the SiO 2/Si substrate, Raman signals from ultra-thin layered materials and the underlying substrate can be significantly enhanced under deep ultraviolet excitation.