Kinematical and dynamical contrast of dislocations in thick GaN substrates observed by synchrotron-radiation X-ray topography under six-beam diffraction conditions
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arXiv
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2025
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| _version_ | 1866914481156653056 |
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| author | Yao, Yongzhao Tsusaka, Yoshiyuki Ishikawa, Yukari |
| author_facet | Yao, Yongzhao Tsusaka, Yoshiyuki Ishikawa, Yukari |
| contents | Dislocations in a thick ammonothermal GaN substrate were investigated using synchrotron-radiation X-ray topography (SR-XRT) under six-beam diffraction conditions. The high brilliance of the synchrotron source enabled the observation of the super-Borrmann effect, which markedly enhanced the anomalous transmission of X-rays through the 350~$μ$m-thick crystal. Systematic variation of the deviation angle~$Δω$ revealed a clear transition from kinematical to dynamical diffraction, consistent with theoretical predictions based on dynamical diffraction theory. By selectively exciting five equivalent two-beam diffraction conditions near the six-beam configuration, the Burgers vectors of individual threading edge dislocations (TEDs) were determined according to the $g\cdot b$ invisibility criterion. The measured dislocation image widths agreed well with calculated values derived from the extinction distance and $|g\cdot b|$ dependence, confirming that most dislocations possess Burgers vectors containing an $a$-type component of $\frac{1}{3}\langle 11\bar{2}0\rangle$ or $\frac{2}{3}\langle 11\bar{2}0\rangle$. These results demonstrate that SR-XRT under multibeam diffraction provides a powerful, nondestructive method for quantitative dislocation analysis in thick GaN crystals, offering valuable insights into defect structures critical for high-performance GaN-based electronic devices. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2510_27597 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Kinematical and dynamical contrast of dislocations in thick GaN substrates observed by synchrotron-radiation X-ray topography under six-beam diffraction conditions Yao, Yongzhao Tsusaka, Yoshiyuki Ishikawa, Yukari Materials Science Dislocations in a thick ammonothermal GaN substrate were investigated using synchrotron-radiation X-ray topography (SR-XRT) under six-beam diffraction conditions. The high brilliance of the synchrotron source enabled the observation of the super-Borrmann effect, which markedly enhanced the anomalous transmission of X-rays through the 350~$μ$m-thick crystal. Systematic variation of the deviation angle~$Δω$ revealed a clear transition from kinematical to dynamical diffraction, consistent with theoretical predictions based on dynamical diffraction theory. By selectively exciting five equivalent two-beam diffraction conditions near the six-beam configuration, the Burgers vectors of individual threading edge dislocations (TEDs) were determined according to the $g\cdot b$ invisibility criterion. The measured dislocation image widths agreed well with calculated values derived from the extinction distance and $|g\cdot b|$ dependence, confirming that most dislocations possess Burgers vectors containing an $a$-type component of $\frac{1}{3}\langle 11\bar{2}0\rangle$ or $\frac{2}{3}\langle 11\bar{2}0\rangle$. These results demonstrate that SR-XRT under multibeam diffraction provides a powerful, nondestructive method for quantitative dislocation analysis in thick GaN crystals, offering valuable insights into defect structures critical for high-performance GaN-based electronic devices. |
| title | Kinematical and dynamical contrast of dislocations in thick GaN substrates observed by synchrotron-radiation X-ray topography under six-beam diffraction conditions |
| topic | Materials Science |
| url | https://arxiv.org/abs/2510.27597 |