High-throughput, non-destructive, three-dimensional imaging of GaN threading dislocations with in-plane Burgers vector component via phase-contrast microscopy

We demonstrate a nondestructive, high-throughput method for imaging dislocations in GaN (0001) using phase-contrast microscopy (PCM). A one-to-one correspondence between threading dislocation contrasts in PCM and multiphoton excitation photoluminescence images confirms that PCM enables the detection of dislocations with in-plane Burgers vector components. The contrast morphology reflects dislocation inclination: vertical dislocations appear as dots, whereas inclined dislocations appear as lines. By shifting the focal plane from the top to the back surface, the three-dimensional propagation paths of dislocations can be traced. Dislocations separated by 1.3 μm are resolved. PCM also reveals scratches, subsurface scratches, facet boundaries, and voids.