AFM Observation of Etch-Pit Shapes on β-Ga<sub>2</sub>O<sub>3</sub> (001) Surface Formed by Molten Alkali Etching

In order to understand the crystal defects of beta-gallium oxide (β-Ga2O3) in more detail, we classified the crystal defects of a 2-inch substrate of β-Ga2O3 (001) single crystal. As a result of observing the etch pits formed by molten alkali etching using scanning electron microscope (SEM) and atomic force microscope (AFM), we succeeded in observing six different etch pit shapes. These etch pit shapes are categorized into “Cicada I type”, “Cicada II type”, “Cannonball type”, “Trapezoid type”, “Bar type”, and “Shell type”. We consider that “Cicada I type” and “Cicada II type” are etch pit shapes caused by planar defects, and “Cannon ball type” is etch pit shapes due to dislocations. In addition, “Trapezoid type”, “Bar type”, and “Shell type” are deduced the result of surface morphology.