Silicon and germanium films epitaxially grown on metal oxide buffer layers on Si(111)
substrates are characterized by different X-ray techniques, transmission electron microscopy and
Raman spectroscopy. Pr2O3 and Y2O3 or a combination of both is used as buffer material. X-ray
pole figure measurements and grazing incident X-ray diffraction prove that epi-semiconductor layers
can be grown single crystalline with exactly the same in-plane orientation as the Si(111) substrate.
Epi-Ge layers show a small fraction (less than 0.5 vol. %) of so-called type B rotation twin
regions located near the oxide-Ge interface. The main structural defects for both epi materials are
micro twin lamellas lying in {111} planes 70° inclined to the wafer surface that may reach through
the whole layer from the oxide interface to the surface. Furthermore, TEM confirms the existence of
stacking faults and threading dislocations. X-ray grazing incident diffraction and Raman measurements
show that epi-Ge layers on Pr2O3 buffer are nearly fully relaxed, while epi-Si layers on
Y2O3/Pr2O3 double buffer are compressive strained depending on their own thickness and the thickness
of the underlying Y2O3 layer. It is demonstrated that the epi-layer quality can be improved by
post-deposition annealing procedures.
Electronic properties of hydrogen storage materials with photon-in/photon-out soft-X-ray spectroscopy