Mapping of Lattice Strain in 4H-SiC Crystals by Synchrotron Double-Crystal X-ray Topography

Abstract

The presence of lattice strain in n-doped 4H-SiC substrate crystals grown by a physical vapor transport method can strongly influence the performance of related power devices that are fabricated on them. Information on the level and the variation of lattice strain in these wafer crystals is thus important. In this study, a non-destructive method is developed based on synchrotron double-crystal x-ray topography to map lattice strains in 4H-SiC wafers. Measurements are made on two 4H-SiC substrate crystals-one is an unprocessed commercial wafer while the other was subject to a post-growth high-temperature heat treatment. Maps of different strain components are generated from the equi-misorientation contour maps recorded using synchrotron monochromatic radiation. The technique is demonstrated to be a powerful tool in estimating strain fields in 4H-SiC crystals. Analysis of the strain maps also shows that the normal strain components vary much more significantly than do the shear/rotation components, indicating that lattice dilation/compression rather than lattice tilt is the major type of deformation caused by both the incorporation of nitrogen dopants and the nucleation of basal plane dislocations.

Strain Recovery and Defect Characterization in Mg‐Implanted Homoepitaxial GaN on High‐Quality GaN Substrates

“…The differences are possibly due to continued evolution of the defect configurations such that there is a change in defect density and morphologies. To investigate this further, double‐crystal X‐ray topography (XRT), which is highly sensitive to lattice imperfections with an angular resolution on the order of arcsec, was used . Synchrotron double‐crystal XRT images at (114) reflection of the unimplanted sample, the as‐implanted sample, and the 1300 °C 100 min sample are shown in Figure .…”

Polytype switching identification in 4H-SiC single crystal grown by PVT

“…Lin et al studied the identification of polytypes 6H and 15R in PVT-grown SiC by Raman spectroscopy and Transmission electron microscopy (TEM) [16] and explained the finite probability of getting 15R-SiC inclusions during the growth of 6H-SiC. Guo et al have studied the lattice strain mapping in 4H-SiC crystals by Synchrotron X-Ray topography and compared it with theoretical calculations [21]. Synchrotron X-ray topography technique was used by many researchers for SiC wafer structural characterization [21,22].…”

Anisotropic mosaicity and lattice-plane twisting of an m-plane GaN homoepitaxial layer

“…To overcome these issues, X-ray rocking curve images have been developed, which provide data on the wafer bending and full width at half maximum (FWHM) over large areas. [22][23][24][25][26][27][28] A recently developed imaging technique for q-vector analysis at two different azimuthal angles shows potential for real industrial applications. 27,28 Moreover, Fourier analysis of the bending angle modulation and FWHM distribution observed by rocking curve imaging have revealed the 29 Therefore, to understand the bending it is necessary apply recently developed X-ray diffraction topography techniques to analyze the FWHM and its distributions over the m-plane GaN.…”