X-ray topography in the study of semiconductors

X-ray topography as a completely nondestructive technique is frequently use d to study crystal defects, deformation fields and compositional changes in semiconductors because of its high sensitivity to strains induced by defec ts in crystals. Principles of surface sensitive reflection Lang topography and reflection double crystal topography and their contrast mechanisms are shortly presented and three examples of their application given. The techni ques have been used to characterize crystal defects such as threading dislo cations arranged into cellular structure and slip bands at surfaces of semi -insulating GaAs substrate wafers, to characterize transformation of thread ing dislocations into misfit dislocations in a InGaAs/GaAs strained quantum well and to characterize misorientation domains in highly mismatched InGaA s/GaAs heterostructures. In the last case tilt regions have been evidenced by synchrotron double crystal topography.