Direct evaluation of threading dislocations in 4H-SiC through large-angle convergent beam electron diffraction

ABSTRACT

In this study, the structures of threading dislocations (TDs) in a 4H-SiC epilayer were directly characterised using large-angle convergent beam electron diffraction (LACBED) via transmission electron microscopy (TEM), by examining the splitting of reflections due to the presence of dislocation lines. Previously, X-ray topography (XRT) mapping in combination with ray-tracing simulations has been shown to be an efficient method for imaging and differentiating common TD types and variants in 4H-SiC. In this work, the validity of XRT-based results was verified by LACBED through direct evaluation and differentiation of the Burgers vectors and physical crystallographic features of all $⟨a⟩$ threading edge, $⟨c⟩$ threading screw, and $⟨c+a⟩$ threading mixed dislocations variants. The LACBED results agreed with the XRT-based results with respect to TD type and variant. The screw-sense or half-plane orientation and Burgers vector determined from LACBED analysis for each TD were self-consistent. For the case of $⟨a⟩$-TEDs, atomic-resolution analysis of the core structure, through high-angle annular dark field scanning TEM, directly revealed two half-planes, each with a $\frac{1}{3}⟨1\overline{1}00⟩$ Burgers vector component, and the sum of these components was confirmed to be $\frac{1}{3}⟨11\overline{2}0⟩$. Finally, an algorithm for efficient LACBED analysis of TDs in 4H-SiC was discussed.

KEYWORDS:

• 4H-SiC
• dislocation
• Burgers vector
• topography
• TEM
• LACBED

Acknowledgements

A part of this work was supported by the Council for Science, Technology and Innovation (CSTI), the Cross-ministerial Strategic Innovation Promotion Program (SIP), ‘Next-generation power electronics/Consistent R&D of next-generation SiC power electronics’ (funding agency: NEDO).

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by Council for Science, Technology and Innovation (CSTI), the Cross-ministerial Strategic Innovation Promotion Program (SIP), “Next-generation power electronics/Consistent R&D of next-generation SiC power electronics” (funding agency: NEDO).