Minute SiGe Quantum Dots on Si(001) by a Kinetic 3D Island Mode

We investigated the initial growth stages of ${\mathrm{Si}}_x{\mathrm{Ge}}_{1-x}/\mathrm{Si}\left(001\right)$ by real time stress measurements and in situ scanning tunneling microscopy at deposition temperatures, where intermixing effects are still minute ( $\le 900\mathrm{K}$). Whereas Ge/Si(001) is a well known Stranski-Krastanow system, the growth of SiGe alloy films switches to a 3D island mode at Si content above $20\%$. The obtained islands are small (a few nanometers), are uniform in shape, and exhibit a narrow size distribution, making them promising candidates for future quantum dot devices.