X-RAY-DIFFRACTION CHARACTERIZATION OF SUPERLATTICES GROWN ON OFFCUT (100) SUBSTRATES

An x-ray diffraction procedure is proposed to fully characterize the structural parameters of superlattices and multiple quantum wells grown on misoriented substrates. The procedure requires the acquisition of x-ray rocking curves, as a function of the azimuthal angle-phi, from which the offcut angle-epsilon and the tilt angle-beta between the (100) planes of the substrate and the superlattice can be measured. The direction of the tilt can also be measured and it is shown on a sample comprising a ten period InGaAs/GaAs superlattice, that this direction is not necessarily coplanar with the surface normal and the GaAs (100) direction. The proposed procedure also includes the fitting of the experimental data using a simulation program which takes into account the values of phi, epsilon, and beta. The simulation program used the kinematical approximation and is based on a simple approach which reproduces the independence of the satellite peak spacing with the azimuth, as observed in the measurements.