Nano-scale characterization and spectroscopy of strained silicon

Abstract

We utilize surface enhancement in Raman scattering to study strain fluctuations in strained silicon (ε-Si). Thin ε-Si layers are covered with thin silver layer to invoke surface enhanced Raman spectroscopy (SERS). Results show that SERS effectively enhance the Raman signal originating from ε-Si layer and it stands distinctly apart from the Raman signal originating from the buffer layer. To increase the spatial resolution and achieve nanoscale spectroscopy, we characterize the sample using point-surface-enhancement such that the apex a silver-coated sharp tip is positioned very close to the sample region. This technique, known as the tip-enhanced Raman spectroscopy (TERS), provides nanometric resolution to observe localized strains and nano-scale variation in Raman frequency. Lastly, we improve the signal-tonoise ratio of TERS two-ways: optical field enhancement using different metallic tip and background signal reduction arising from bulk materials.