A procedure which was based upon the stacking sequences of semiconductor structures was proposed for the determination of the possible dislocation structures of interface steps between 2 different polytypes. It was also applied to the interface between 2H, and 3C, 4H and 6H polytypes. Three different possible dislocations were found, with Burgers vectors of 1/6<20•3>, 1/3<10•0> and 1/2<00•1>. A high-resolution electron microscopic study, of the particular case of 2H-AlN on 6H-SiC, revealed only 2 types of interface step. This result was in agreement with the assumption that the growth of AlN always began at the wurtzite position on the surface of the substrate. One type of interface step was found to generate an extended defect, in the AlN layer, which folded from the basal plane to the prismatic plane. Although the prismatic defect was not seen edge-on, image simulation permitted the identification of a 1/2<00•1> fault vector which was contained in the fault plane. The formation of such a defect was attributed to the growth mode of AlN on -SiC.

P.Vermaut, P.Ruterana, G.Nouet, H.Morkoç: Philosophical Magazine A, 1997, 75[1], 239-59