Structural investigation of SiC epitaxial layers grown under microgravity and on-ground conditions

• Thick 4H-, and 6H-SiC epitaxial layers have been grown by LPE from Si-Sc-C solvent at microgravity conditions during a space experiment, as well as on-ground. The samples are characterised by cross-sectional TEM and HRXRD. Layers grown at microgravity are relatively defect free, although their surfaces are always stepped. Control samples grown on-ground have similar surface appearance, but contain scandium carbide precipitates, nanopipes, micropipes and/or cavities as verified by TEM. However, none of the aforementioned defects was traced in the layers grown at microgravity conditions. So, samples grown at space microgravity conditions are superior in their defect structure to those ones grown on the ground. The defects called nanopipes can be described as empty pipes of about 200 nm diameter traversing the layer in the [0001] (growth) direction. The steps in the microgravity and on-ground samples have facets of {104} type crystallographic planes both in 6H-, and 4H-SiC. We suggest, that those facets are formed and preferred during growth due to a possible mechanism of decreasing the high energy of the growing Si terminated (0001) surface. (C) 1999 Elsevier Science S.A. All rights reserved.

Nyckelord

silicon carbide

liquid phase epitaxy

microgravity

transmission electron microscopy

defects

nanopipes

TECHNOLOGY

TEKNIKVETENSKAP

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)