Nondestructive dislocation delineation using topographically enhanced imaging of surface morphologies in 4H-SiC epitaxial layers

The morphology of surface features generated by dislocations present at 4H-SiC epitaxial layer surfaces was investigated by forescattered electron detection (FED) inside a conventional scanning electron microscope. Various growth pit morphologies were correlated to dislocation types using molten KOH...

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Veröffentlicht in:Journal of applied physics 2008-04, Vol.103 (7)
Hauptverfasser: Picard, Yoosuf N., Liu, Kendrick X., Stahlbush, Robert E., Twigg, Mark E., Zhang, Xuan, Skowronski, Marek
Format: Artikel
Sprache:eng
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Zusammenfassung:The morphology of surface features generated by dislocations present at 4H-SiC epitaxial layer surfaces was investigated by forescattered electron detection (FED) inside a conventional scanning electron microscope. Various growth pit morphologies were correlated to dislocation types using molten KOH etching. Specifically, sharp-apex pits and stripe-shaped pits were consistently linked to screw and edge dislocations, respectively. The size and depth of these growth pits were measured by atomic force microscopy (AFM). Tail-like features were observed by FED emanating from sharp-apex pits and verified by Nomarski optical microscopy (NOM). A mechanism is proposed to explain the FED contrast exhibited by these tail-like features. This mechanism relates the nature of step-flow and spiral growth in the wake of a screw dislocation to the surface distortions resulting in such tail-like features. The Burgers vector direction can thus be determined based on a purely morphological analysis of these tail-like features. The results of this study illustrate the various capabilities of FED for surface imaging as compared to AFM and NOM. The potential for utilizing FED to map dislocation-associated growth pits is discussed.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.2903873