Abstrakt
Growing low-defect Ge layers on Si substrate is of increasing interest nowadays because of its possible application in CMOS technologies and optoelectronics. Nanoheteroepitaxy is a novel approach to decrease the elastic lattice misfit energy in Ge layer below the nucleation energy of defects and consequently reduce the amount of dislocations in Ge layers.
The elastic energy reduction can be reached by deposition of Ge on laterally structured Si substrates containing small zero- or one-dimensional nanostructures like pillars or wires. Then the accommodation of the lateral Si lattice parameter of the nanostructures to that of the above-deposited Ge lattice provides the strain-relieving mechanism.
The efficiency of the nanoheteroepitaxy growth is substantially affected by a residual deformation in the Si nanostructures caused by lithography oxide mask. We have studied this deformation by high-resolution x-ray diffraction mapping.
The experimental data obtained from samples with and without oxide masks were compared to simulations based on finite-element calculation of the strain and kinematical scattering theory. From the comparison we determined the parameters of elastic interaction of the mask material with Si nanostructures.
We have clearly demonstrated that the oxide masks obstruct the strain relieving process.