Structural characterization of the grown crystal/seed interface of physical vapor transport grown 4H-SiC crystals using Raman microscopy and x-ray topography

• Published in: Journal of crystal growth 2019-06, Vol.515, p.58-65
• Main Authors: Shioura, Kentaro, Shinagawa, Naoto, Izawa, Takuto, Ohtani, Noboru
• Format: Article
• Language: English
• Subjects: A1. Defects; A1. Interfaces; A1. Optical microscopy; A1. X-ray topography; A2. Growth from vapor; B2. Semiconducting materials; Basal plane; Boules; Coupled modes; Crystal defects; Crystal growth; Crystal structure; Crystallography; Crystals; Defects; Dislocations; Microscopy; Single crystals; Structural analysis; Topography; Transport; Wafers; X ray topography
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2019.03.015

•Defects at and near the growth interface of PVT-grown 4H-SiC crystals have been investigated.•4H-SiC wafers containing a beveled growth interface were prepared from 4H-SiC crystals.•There existed basal plane dislocation (BPD) networks at the growth interface.•The BPD networks largely extended deep inside the seed crystal.•These results suggested the vacancy injection occurring during the initial stage of SiC PVT growth. The defect structure at and near the grown crystal/seed interface of 4H-SiC single crystals grown by the physical vapor transport (PVT) growth method has been investigated using Raman microscopy and x-ray topography. To examine the detailed distribution of crystallographic defects across the interface, 4H-SiC wafers containing a beveled growth interface were prepared from nitrogen-doped 4H-SiC single crystal boules; the beveled interface allows more spatially resolved observations of the defect structure near the interface compared to the interface on vertically sliced [e.g., (112¯0) and (11¯00)] wafers. Raman microscopy imaging using the longitudinal optical phonon-plasmon coupled (LOPC) mode determined the position of the growth interface and revealed several characteristic features of the interface through the analyses of the scattering intensity, peak position, and width of the LOPC mode peak. X-ray topography revealed that there existed networks of basal plane dislocations at the growth interface, and they extended deep inside the seed crystal. Based on these observations, we discussed the defect formation process at the initial stage of PVT growth and suggested an important role of vacancy injection during PVT growth of SiC.