Defect generation behavior in Czochralski-grown ScAlMgO4 crystal using synchrotron X-ray topography

Abstract

Synchrotron X-ray topography was employed to characterize the defect structure and investigate the defect generation process in Czochralski (CZ)-grown ScAlMgO4 (SAM) crystals. In the X-ray topographs of the <2¯ 0 2 0>, <2¯ 0 2 22>, and 0 0 0 24 diffractions of a SAM(0 0 0 1) in-plane wafer, straight- and stream-type dislocations were analyzed using the extinction rule. These dislocations were ascertained to have both <1¯1¯ 2 0> and <0 0 0 1> components of the Burgers vector. A SAM(0 1¯ 1 0) cross-section wafer was then observed by X-ray topography to investigate the generation process of the defect structure. Straight-type dislocations along [1¯ 0 1 0], [0 1 1¯ 0], and [1 1¯ 0 0] were generated at the early-growth stage, to release accumulated large thermal strain derived from the solid–liquid phase change. Dislocation-free regions and low-dislocation density regions, including stream- and edge-type dislocations, appeared in the late-growth stage. The weak contrast of the growth-striation in the late-growth stage indicates the reduction in strain. The reduced strain is considered to have generated dislocation-free and low-dislocation density regions. The dislocation structure in SAM reflected the behavior of the thermal strain during the CZ-growth.