X-ray Diffraction Analysis of Surface Si Nanostructures Used for Ge Nanoheteroepitaxy
J. Matejova1,2, G. Kozlowski1, P. Zaumseil1, V. Holy2 and T. Schroeder1
1 IHP, Im Technologiepark 25, D-15236
Frankfurt (Oder), Germany
2
Faculty of Mathematics and Physics,
matejova@ihp-microelectronics.com
Integrating low-defect Ge
layers on Si substrate is of increasing interest due to its possible
applications in optoelectronics and CMOS technologies. To avoid nucleation of
dislocations caused by relatively large lattice mismatch between Si and Ge, nanoheteroepitaxy
strain-relieving mechanism was suggested [1]. To prove the functionality of
this mechanism, we investigate the strain field in Si line nanostructures
covered by SiO2 growth mask. By comparison of experimental XRD data
with simulations (X-ray kinematical scattering theory), we refined the shape
coordinates of the nanostructures taken from TEM images. We carried out a
strain field simulation based on elasticity theory and showed insufficiency of
conventional model of the strain in Si after thermal oxidation. Therefore we
suggested an iterative evolutionary algorithm to determine the strain field
from the experimental XRD data. Preliminary results, where we reached better
agreement, are shown.
(extended contribution submitted)