Intersecting faults on basal and prismatic planes in aluminium nitride

Abstract

Intersecting faults on basal (0001) and prismatic (1210) planes in A1N (hexagonal, wurtzite structure) have been studied by diffraction contrast with the electron microscope. The faults on (1210) had fault vectors 3/2 p + 1/2 c=½[1011], as deduced from the observed vanishing conditions. The expected stair-rod dislocations at the intersections of the faults have been found, and they had screw components to their Burgers vectors. An atomic model for the faults on (1210) is proposed, and possible mechanisms of formation during crystal growth are discussed. The determination of the nature of faults in hexagonal crystals by means of diffraction contrast is considered in detail, since the information obtainable is different for h.c.p. than for f.c.c.