Study of defect structures in 6H-SiC a/m-plane pseudofiber crystals grown by hot-wall CVD epitaxy
- Stony Brook Univ., Stony Brook, NY (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- NASA Glenn Research Center, Cleveland, OH (United States)
Structural perfection of silicon carbide (SiC) single crystals is essential to achieve high-performance power devices. A new bulk growth process for SiC proposed by researchers at NASA Glenn Research Center, called large tapered crystal (LTC) growth, based on axial fiber growth followed by lateral expansion, could produce SiC boules with potentially as few as one threading screw dislocation per wafer. In this study, the lateral expansion aspect of LTC growth is addressed through analysis of lateral growth of 6H-SiC a/m-plane seed crystals by hot-wall chemical vapor deposition. Preliminary synchrotron white-beam x-ray topography (SWBXT) indicates that the as-grown boules match the polytype structure of the underlying seed and have a faceted hexagonal morphology with a strain-free surface marked by steps. SWBXT Laue diffraction patterns of transverse and axial slices of the boules reveal streaks suggesting the existence of stacking faults/polytypes, and this is confirmed by micro-Raman spectroscopy. Transmission x-ray topography of both transverse and axial slices reveals inhomogeneous strains at the seed–epilayer interface and linear features propagating from the seed along the growth direction. Micro-Raman mapping of an axial slice reveals that the seed contains high stacking disorder, while contrast extinction analysis (g·b and g·b×l) of the linear features reveals that these are mostly edge-type basal plane dislocations. Further high-resolution transmission electron microscopy investigation of the seed–homoepilayer interface also reveals nanobands of different SiC polytypes. A model for their formation mechanism is proposed. Lastly, the implication of these results for improving the LTC growth process is addressed.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC00112704
- OSTI ID:
- 1328371
- Report Number(s):
- BNL-112675-2016-JA; KC0403020
- Journal Information:
- Journal of Electronic Materials, Vol. 45, Issue 4; ISSN 0361-5235
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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