Defects associated with rectangular-like and assault boat-shaped etch pits in β -Ga2O3 substrates

Crystal defects critically limit the material quality and device performance of β-Ga2O3, yet the crystallographic defects associated with etch pits formed during wet chemical etching remain poorly understood. Here, two previously unreported etch pit morphologies in (100)- and (001)-oriented β-Ga2O3 substrates are systematically investigated by combining wet chemical etching with transmission electron microscopy. A representative rectangular-like etch pit with a distinct core on the (100) substrate is associated with a dislocation having a Burgers vector b//⟨13-2⟩, which has not previously been reported for dislocations in β-Ga2O3. In contrast, a representative assault boat-shaped etch pit on the (001) substrate is associated with the coexistence of (100) stacking faults, (100) twin boundaries, and a dislocation, with the (100) twin boundaries induced by the (100) stacking faults. These results provide direct microscopic insight into the defect structures associated with these previously unreported etch pit morphologies in β-Ga2O3 and offer a basis for defect identification and evaluating the impact of these defects on device performance.