Radiation tolerance is determined as the ability of crystalline materials to withstand the accumulation of the radiation induced disorder. Nevertheless, for sufficiently high fluences, in all by far known semiconductors it ends up with either very high disorder levels or amorphization. Here we show that gamma/beta (γ/β) double polymorph Ga₂O₃ structures exhibit remarkably high radiation tolerance. Specifically, for room temperature experiments, they tolerate a disorder equivalent to hundreds of displacements per atom, without severe degradations of crystallinity; in comparison with, e.g., Si amorphizable already with the lattice atoms displaced just once. We explain this behavior by an interesting combination of the Ga- and O- sublattice properties in γ-Ga₂O₃. In particular, O-sublattice exhibits a strong recrystallization trend to recover the face-centered-cubic stacking despite the stronger displacement of O atoms compared to Ga during the active periods of cascades. Notably, we also explained the origin of the β-to-γ Ga₂O₃ transformation, as a function of the increased disorder in β-Ga₂O₃ and studied the phenomena as a function of the chemical nature of the implanted atoms. As a result, we conclude that γ/β double polymorph Ga₂O₃ structures, in terms of their radiation tolerance properties, benchmark a class of universal radiation tolerant semiconductors.

Ion implantation induced phase transformation and the crystal structure of a series of ion implanted β-Ga₂O₃ samples were studied using electron diffraction, high resolution transmission electron microscopy, and scanning transmission electron microscopy. In contrast to previous reports suggesting an ion implantation induced transformation to the orthorhombic κ-phase, we show that for ²⁸Si⁺, ⁵⁸Ni⁺, and stoichiometric ⁶⁹Ga⁺/¹⁶O⁺-implantations, the monoclinic β-phase transforms to the cubic γ-phase. The γ-phase was confirmed for implantations over a range of fluences from 10¹⁴ to 10¹⁶ ions/cm², indicating that the transformation is a general phenomenon for β-Ga₂O₃ due to strain accumulation and/or γ-Ga₂O₃ being energetically preferred over highly defective β-Ga₂O₃.

Disordering of solids often leads to amorphization, but polymorph transitions, facilitated by favorable atomic rearrangements, may temporarily help to maintain long-range periodicity in the solid state. In far-from-equilibrium situations, such as atomic collision cascades, these rearrangements may not necessarily follow a thermodynamically gainful path, but may be kinetically limited. In this Letter, we focus on such crystallization instead of amorphization in collision cascades in gallium oxide (Ga_{2}O_{3}). We determine the disorder threshold for irreversible β→γ polymorph transition and explained why it results in elevating energy to that of the γ polymorph, which exhibits the highest polymorph energy in the system below the amorphous state. Specifically, we demonstrate that upon reaching the disorder transition threshold, the Ga sublattice kinetically favors transitioning to the γ-like configuration, requiring significantly less migration for Ga atoms to reach the lattice sites during postcascade processes. As such, our data provide a consistent explanation of this remarkable phenomenon and can serve as a toolbox for predictive multipolymorph fabrication.

Disorder-induced ordering and remarkably high radiation tolerance in γ-phase of gallium oxide is a recent spectacular discovery at the intersection of the fundamental physics and electronic applications. Importantly, by far, these data were collected with initial samples in form of the thermodynamically stable β-phase of this material. Here, we investigate these phenomena starting from metastable α-phase and explain radically new trend occurring in the system. We argue that in contrast to that in β-to-γ disorder-induced transitions, the O sublattice in α-phase exhibits hexagonal close-packed structure, so that to activate α-to-γ transformation significant structural rearrangements are required in both Ga and O sublattices. Moreover, consistent with theoretical predictions, α-to-γ phase transformation requires accumulation of the substantial tensile strain to initiate otherwise impossible lattice glides. Thus, we explain the experimentally observed trends in term of the combination of disorder and strain governed process. Finally, we demonstrate atomically abrupt α/γ interfaces paradoxically self-organized out of the stochastic disorder.

In situ TEM heating studies of double γ/β-Ga ₂ O ₃ polymorph structures revealed γ-to-β polymorph transition via the formation of β-Ga ₂ O ₃ domains.

ZnFe ₂ O ₄ nanoparticles and Fe-decorated inversion domain boundaries in ZnO both have their absorption band edge at 2.0 eV, determined by DRS and EELS. The similarity is attributed to the presence of layers of Fe ³⁺ octahedrally coordinated by oxygen.