Strain relaxation in Ge microcrystals studied by high-resolution X-ray diffraction

Deposition on patterned substrates is a promising method for obtaining high quality, strain and defect free heteroepitaxial layers. In this paper we investigate the crystalline structure of quasi-continuous Ge layers consisting of closely spaced microcrystals on a Si substrate patterned in the form of a regular net of lithographically defined squared based pillars. Lattice parameters, strain and degree of relaxation of the Ge microcrystals are measured by standard high-resolution X-ray diffraction using reciprocal space mapping. In particular, we focus on the impact of Si pillar size and spacing on the Ge crystal quality by analyzing how the bending of crystal lattice planes caused by thermal stress relaxation and random crystal tilts affect the width of the diffraction peaks.