Observation of columnar microstructure in step-graded Si_1-xGe_x/Si films using high-resolution X-ray microdiffraction

High angular resolution x-ray microdiffraction was used to determine columnar microstructure in step-graded Si1-xGex/Si(001) structures with low threading dislocation densities. Experiments were performed with a high brilliance x-ray undulator source at the 2-ID-D end station. Rectangular columnar micrograins were found with average widths from ∼0.6 to ∼3.7 μm. Many sharp peaks of a 3- μm-thick strain-relaxed Si0.83Ge0.17 film were observed using x-ray rocking curves.