Effects of substrate miscut on dislocation glide in metamorphic (Al) GaInP buffers

The effects of miscut toward (111)A of (001) GaAs substrates on α dislocation glide in compositionally step-graded (Al)GaInP buffers grown by metal-organic chemical vapor deposition have been investigated. The full width at half maximum of X-ray rocking curves and the tilt obtained from symmetric (004) reciprocal space mappings suggest that the average misfit glide length of α dislocations is longer in samples on 15° off substrates than that on 7° off substrates. Compared to the 7° sample, the larger miscut 15° more significantly weakens the blocking effect of the β dislocations on the motion of α dislocations, and it also provides a much stronger driving force on α dislocations in (111) slip planes, which greatly enhances the misfit dislocation glide. Eventually, the two effects collectively lead to a longer average misfit glide length of α dislocations and a lower threading dislocation density in the active layer on the 15° off substrates, which is critical for improving the performances of devices based on lattice mismatched materials.