UCLA

GaAs-based compositionally graded buffer layers were investigated to determine the strain relaxation as a function of growth as well as whether ordering plays a role in the change in the strain relaxation mechanisms. X-ray reciprocal space mapping of (004) and (224) lattice points was employed to characterize the composition, tilt, lattice parameter and strain state of the step-grade layers. No CuPt ordering was observed in either x-ray diffraction or TEM, and the lack of observed ordering shows that the changes in the strain relaxation mechanisms do not necessarily depend on ordering.