X-RAY CHARACTERIZATION OF DEFECT STRUCTURE IN LEC GAAS CRYSTALS

Semi-insulating (SI) GaAs crystals grown by LEC technique contain as the trade mark of this method at present level of technology complicated network of defects frequently called cellular structure. Structure and properties of this feature being in the mainstream of interest of GaAs investigations still should be considered as far from being fully understood. We report here features of images recorded by means of X-ray diffraction, electron microscopy and after photoetching obtained for an As-rich, undoped, semi-insulating GaAs crystals grown by LEC technique. For the formation of cellular network instead of simplified dislocation only based structure we postulate that As precipitates, impurities and dislocations could form image constituting the real cellular structure.