Three-Dimensional Observation of Internal Defects in a β-Ga2O3 (001) Wafer Using the FIB-SEM Serial Sectioning Method
We reported our observation results on the etch pit shapes on β-Ga2O3 (001) wafers using a scanning electron microscope (SEM) and an atomic force microscope (AFM) in a previous study. However, it was difficult to detect the internal crystal defects that exist under the etch pits. In this study, to gain a detailed understanding of the internal crystal defects under the etch pits in detail, we observed the etch pits on the (001) surface three-dimensionally using a focused ion beam-SEM. The etch pits investigated were "Cicada I" and "Cicada II," which had the characteristic shapes observed in previous SEM and AFM analysis. Using this method, we revealed the existence of plate-like defects along the (100) plane under the etch pits. The proposed method is useful for understanding internal defects the etch pits which cannot be clarified by observing the surface using SEM and AFM analysis. Furthermore, from the changes in the SEM image contrast, Cicada I and Cicada II were deduced to be internal planar defects, i.e., plate-like voids and stacking faults, respectively.