Observation of dislocations in thick β-Ga2O3 single-crystal substrates using Borrmann effect synchrotron x-ray topography

Abstract

We performed Borrmann effect x-ray topography (XRT) to observe dislocations and other structural defects in a thick β-Ga2O3 (001) substrate. The Borrmann effect was realized by working in a symmetrical Laue geometry ( g = 020). Anomalous transmission occurred under the exact Bragg condition, producing a strong diffraction beam that allowed us to image defects across the entire thickness of the substrate. The analysis clearly revealed straight b-axis screw-type and curved dislocations and allowed assessing the corresponding behaviors. Other structural defects, including pipe-shaped voids and dislocation loops produced by mechanical damage, were also observed. Finally, we compared Borrmann effect transmission topography and conventional reflection topography and explained the appearance of some characteristic defects in the two modes. Our results show that Borrmann effect XRT is a powerful and effective technique to study the spatial distribution and structural properties of defects in highly absorbing β-Ga2O3.

Lattice misorientation at domain boundaries in β‐Ga2O3 single‐crystal substrates observed via synchrotron radiation X‐ray diffraction imaging and X‐ray reticulography

“…Maps of maximum intensity, peak position, and full width at half maximum (FWHM) were then constructed 29 from the images using a homemade program. XRR and XRT images were also recorded on X‐ray films (Agfa Structurix D2) to analyze the misorientation and the dislocations nucleated at the DBs 22 in detail.…”

“…This requires several key technologies to suppress the generation of lattice defects. Typical lattice defects in bulk substrates include dislocations, [12][13][14][15][16] stacking faults, [17][18][19] voids, 10,[20][21][22] and domain boundaries (DBs). 6 Compared to the other three major defect types, DB has drawn little attention from researchers.…”