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arXiv · 2604.04318

Kinetics studies on $\kappa$ to $\beta$-Ga$_2$O$_3$ phase transformations via in-situ high temperature X-ray diffraction

Jingyu Tang·Po-Sen Tseng·Kunyao Jiang·Rachel C. Kurchin·Robert F. Davis·Lisa M. Porter
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Abstract

The kinetics of the $\kappa$ to $\beta$-Ga$_2$O$_3$ phase transformation were investigated in five batches of nominally phase-pure $\kappa$-Ga2O3 thin films heteroepitaxially grown on c-plane sapphire, with film thickness ranging from 700 to 1100 nm, using in-situ high-temperature X-ray diffraction. Phase fractions were quantitatively extracted through modified Rietveld refinement that accounts for preferred orientation, and the transformation kinetics were analyzed using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. The applicability of the JMAK model to thin-film materials was evaluated and its lower and upper bounds for thin films and bulk materials were established. Based on this analysis, a method specifically suited for thin-film kinetic studies was developed and yielded reproducible and robust results across all five sample batches. The results indicate that the $\kappa$ to $\beta$ phase transformation in ~700-1100 nm films is best described as an interface-controlled, site-saturated nucleation with thickness-limited or effectively two-dimensional growth.

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Jingyu Tang, Po-Sen Tseng, Kunyao Jiang, Rachel C. Kurchin, Robert F. Davis, Lisa M. Porter. 2026-04-05. Kinetics studies on $\kappa$ to $\beta$-Ga$_2$O$_3$ phase transformations via in-situ high temperature X-ray diffraction. https://arxiv.org/abs/2604.04318

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