Using synchrotron radiation x-ray multiple diffraction to examine the lattice coherency of semiconductor surfaces and epitaxial layers

An experimental facility for carrying out x-ray multiple diffraction (XRMD) studies in parallel-beam geometry using the Daresbury synchrotron radiation source and its application in the study of coherency of an epilayered sample are described. Experimental high-resolution Renninger scans (RS) about GaAs(006) are presented and the pseudoforbidden "Aufhellung" eight-beam (000,006,020,042,044,026,024,022) case has been fully resolved for the first time using the setup which involves a double-crystal six-circle scattering geometry and data acquisition providing optimal conditions for these scans to be obtained. A sample of InGaAs/AlGaInAs/InP(001) epilayered material was also examined and high-resolution RS from the bulk, substrate, and epitaxial overlayers were obtained. The diffraction wavelength used was determined directly from the bulk RS as ?=(1.4695±0.0005) Å. The data clearly reveal a number of interesting XRMD features which allow for the sample characterization. The layer parallel lattice parameter can be determined either from the epilayer tetragonal distortion in the layer RS or from the MORSI (modulation of the RS intensity due to the presence of the epilayers) [Greenberg & Ladell, Appl. Phys. Lett. 50, 436 (1987)] dips in the substrate RS. These dips can also provide simultaneous information on relative tilt and rotation between both layer/substrate lattices. The fitting of the position and profile of the three-beam surface peaks allows the determination of the layer parallel lattice parameter and the layer mosaic spread on the sample surface plane. © 1996 American Institute of Physics.