Anisotropic radius of curvature of crystal planes in wide-bandgap semiconductor wafers measured by X-ray diffraction

Abstract

Conventionally, the radius of curvature of crystal planes in a wafer is measured by position-dependent X-ray diffraction (XRD) along a particular diagonal direction of the wafer. However, we show herein that this method is not reliable for assessing the wafer’s real three-dimensional curvature. Using commercial 2 inch 4H-SiC, GaN, AlN, and β-Ga2O3 wafers, we demonstrate that the choice of the diagonal direction along which the position-dependent XRD was acquired strongly affects not only the apparent radius of curvature but also whether it is convex or concave.