High-speed, high-resolution, three-dimensional imaging of threading dislocations in β-Ga2O3 via phase-contrast microscopy

This study presents a nondestructive and laboratory-accessible approach for high-speed, high-resolution three-dimensional characterization of threading dislocations in β-Ga2O3 (010) single crystals using phase-contrast microscopy (PCM). The accurate wafer-scale evaluation of dislocations in β-Ga2O3 is essential for improving crystal quality and device reliability in ultrawide-bandgap semiconductor materials; however, existing nondestructive techniques, capable of three-dimensional characterization, are limited in accessibility and throughput. The capability of PCM to detect threading dislocations in β-Ga2O3 is quantitatively validated through a one-to-one correspondence with synchrotron radiation x-ray topography (SR-XRT) images obtained from the same regions. Compared with SR-XRT, PCM provides enhanced in-plane spatial resolution, enabling the separation of closely spaced dislocations. By systematically shifting the focal plane, PCM allows the direct visualization of dislocation propagation along the depth direction. Furthermore, the projection of stacked PCM images enables tracing of dislocation lines in the in-plane direction, providing insight into dominant slip planes and average inclination angles in β-Ga2O3. These results demonstrate that PCM serves as a practical materials characterization tool for nondestructive, three-dimensional evaluation of threading dislocations in β-Ga2O3 wafers, offering significant potential for crystal growth optimization and reliability assessment of β-Ga2O3 and related wide-bandgap semiconductor materials.