STRUCTURE OF PLANAR AGGREGATES OF SI IN HEAVILY SI-DOPED GAAS

Planar defects on {111} planes in heavily Si-doped boat-grown GaAs crystals have been studied with a high-resolution technique in transmission electron microscopy and energy-dispersive X-ray analysis. There are two sizes of defect, both of which are considered to be Si aggregates, precipitated in a GaAs matrix and forming interstitial-type stacking faults. The Burgers vector of the defects are of (a/3)[111], the same as that of an extrinsic Frank loop. The larger loops form triangles with such orientations as to constitute the surfaces of a tetrahedron. This effect is discussed by considering the type of partial dislocations around the defect.