Defect structures and (001) slip in β -Ga2O3 crystal grown by the vertical Bridgman method

Defect structures in bulk β-Ga2O3 crystals grown by the vertical Bridgman (VB) method were investigated using synchrotron x-ray topography and compared with those in edge-defined film-fed (EFG) crystals. Linear defects elongated along the b axis, commonly observed at high density in EFG-grown wafers, are largely suppressed in VB-grown samples. As a result, the threading dislocation density is reduced from 2–8 × 104 cm−2 in EFG wafers to 4–7 × 103 cm−2 in VB wafers. The reduced defect density enables clear visualization of dislocation configurations. VB-grown (001) wafers exhibit well-developed in-plane dislocation networks, while (010) wafers show aligned outcrops corresponding to dislocations confined to the (001) plane. These observations indicate that the (001) plane acts as an active slip plane in β-Ga2O3. A crystal-chemical analysis based on bond valence suggests that anisotropic Ga–O bonding weakens interplanar coupling across the (001) plane, providing a possible origin for the observed slip behavior.