Growth of highly strained germanium dots on Si(001) covered by a silicon nitride layer

Abstract

We show that germanium dots can be directly grown by molecular beam epitaxy on a silicon (001) surface covered by a very thin (1.5 nm thick) silicon nitride layer. We describe the experimental procedure, which induces the growth of nano-metric size, isolated germanium dots. The germanium dots are in epitaxy with the silicon substrate. Using grazing incidence x-ray diffraction we show that for very small dots the in-plane lattice parameter inside the dots is very close to the silicon lattice parameter while a strong lattice relaxation and/or silicon inter-diffusion take place with increasing dot size.