Observation of local lattice tilts in strain-relaxed Si1-xGex using high resolution channeling contrast microscopy

A ‘cross-hatch’ morphology is often seen in strain-relaxed Si1-xGex virtual substrates grown using the compositional grading technique. High resolution channeling contrast microscopy measurements, which probe both laterally and vertically into the structure, have revealed the association of such cross-hatch patterns with local lattice-plane bending. In this work, we report the influence of the growth temperature on the extent of the local lattice tilts determined from the channeling contrast measurements. Lines of pileup threading dislocations observed on the surface have also been imaged for the first time, providing us with information on their influence on the lattice-tilt arrangements and orientations.