DETERMINATION OF INTERFACIAL STRAIN DISTRIBUTION IN QUANTUM-WIRE STRUCTURES BY SYNCHROTRON X-RAY-SCATTERING

High-resolution grating x-ray diffraction from a periodic quantum-wire structure is shown to be highly sensitive to strain-field variations near a surface or an interface. Information on two types of strain gra dients can be obtained: a longitudinal gradient, which can produce asy mmetric diffraction profiles, and a transverse gradient, which can gen erate additional diffuse intensity streaks in reciprocal space. These effects are demonstrated in st synchrotron x-ray experiment on an In0. 2Ga0.8As/GaAs quantum-wire array. Kinematical diffraction theory is us ed to describe the diffraction patterns and is found to agree very wel l with the experimental results.