[20a-PA6-1~9] 15.7 Crystal characterization, impurities and crystal defects

▲ [20a-PA6-9] Lattice-plane orientation mapping of 2-inch homo-epitaxial GaN (0001) thin films by grazing incident x-ray diffraction topography

〇(PC)Jaemyung Kim¹, Okkyun Seo¹, Chulho Song¹, Satoshi Hiroi¹, Yanna Chen¹, Yoshihiro Irokawa¹, Toshihide Nabatame¹, Yasuo Koide¹, Osami Sakata¹ (1.NIMS)

Keywords:X-ray topography, GaN, Wafer bending

Characterization of the lattice-plane orientation of a whole wafer is fundamentally important for improving crystal quality. We propose a method for evaluation of the lattice-plane orientation using grazing incident synchrotron X-ray diffraction topography. The sample was a p-GaN/undoped-GaN/2-inch GaN (0001) wafer. The GaN (11-24) diffraction peak and its rocking curve at every point in the wafer were recorded using a two-dimensional area detector in a short amount of time using monochromatic X-rays. In addition, we describe how to reconstruct a [0001] vector with q_x, q_y, and q_z components based on a Cartesian coordinate system of the physical surface of the sample using a matrix obtained from two equivalent (11-24) diffraction topographic images. We were able to obtain the q_x, q_y, and q_z components of every point of the 2-inch wafer from the images recorded at azimuthal angles of 0 and 120°. The vector analysis indicated that the lattice planes of GaN (11-24) were cylindrical rather than spherical. This proposed method could be used to evaluate the orientation mapping of crystal planes that are almost parallel to the sample surface.