Strain in Nanoscale Germanium Hut Clusters on Si(001) Studied by X-Ray Diffraction

Scanning tunneling microscopy and synchrotron x-ray diffraction have been used to investigate nanoscale Ge hut clusters on $\mathrm{Si}\left(001\right)$. We have been able to identify the contributions to the scattered x-ray intensity which arise solely from the hut clusters and have shown that x-ray diffraction can be very sensitive to the strain field in the hut clusters. At the Ge/Si interface the Ge clusters are almost fully strained with a misfit of only 0.5% but towards the apex of the clusters the strain is relaxed and the atomic spacing is close to the natural Ge lattice spacing with a 4.2% misfit.