Synchrotron-radiation X-ray topography and reticulography of bulk $\beta$-Ga$_2$O$_3$ crystals grown from a crucible-free melt

TL;DR

This study uses synchrotron X-ray topography and reticulography to analyze the structural quality and defect formation in bulk $eta$-Ga$_2$O$_3$ crystals grown via the oxide crystal growth from cold crucible method, revealing defect distributions and growth-induced misorientations.

Contribution

It provides detailed insights into defect structures and growth-induced misorientations in $eta$-Ga$_2$O$_3$ crystals grown by OCCC, aiding optimization of growth conditions.

Findings

High crystalline quality beneath the seed with 26 arcsec FWHM

Twist-type lattice misorientation develops during diameter enlargement

Screw dislocations dominate defect structure with densities of ~$10^{5}$cm$^{-2}$ in the central region and ~$10^{6}$cm$^{-2}$ in the wing region

Abstract

The structural properties of a $\beta$-Ga$_2$O$_3$ single crystal grown by the oxide crystal growth from cold crucible (OCCC) method were investigated using synchrotron radiation X-ray topography and X-ray reticulography. The region grown beneath the seed exhibits high crystalline quality with a rocking curve full width at half maximum of about 26 arcsec. During diameter enlargement, a twist-type lattice misorientation develops between the central and laterally expanded regions, originating near the shoulder and propagating along boundaries parallel to the $\langle010\rangle$ growth direction. Dislocation analysis reveals that $\langle010\rangle$-oriented screw dislocations dominate the defect structure with densities of ~$10^{5}$cm$^{-2}$, while higher densities (~$10^{6}$cm$^{-2}$) appear in the wing region. These results clarify defect formation in OCCC-grown $\beta$-Ga$_2$O$_3$ and provide insights for optimizing growth conditions.