Strain and Intermixing in Single Ge/Si Quantum Dots Observed by Tip‐enhanced Raman Spectroscopy

Tip‐enhanced Raman spectra of as‐grown self‐assembled Ge/Si quantum dots have been observed with nano‐scale spatial resolution. It is found that the Ge‐Ge and Si‐Ge modes in the Raman spectra were significantly enhanced only when the tip was on the Ge/Si dots. The Ge content in a single dot was estimated from the relative intensity of the Ge‐Ge and Si‐Ge modes. It is also found that the Si substrate peak at 520 cm−1 was shifted considerably in the neighborhood of the Ge/Si dots. This means that the Si substrate suffers stress around the dots.