Self-assembling of multilayered polymorphs with ion beams

TL;DR

This study demonstrates a novel ion beam technique to self-assemble multilayered polymorphs in gallium oxide, maintaining crystal quality and enabling new material functionalities without traditional synthesis challenges.

Contribution

It introduces a disorder-induced ordering method using ion beams to create multilayered polymorph structures with controlled interfaces in a single step.

Findings

Multilayered polymorph interfaces achieved via ion irradiation.

Crystallographic relationships preserved across interfaces.

Optical mapping confirms structural integrity.

Abstract

Polymorphism contributes to the diversity of nature, so that even materials having identical chemical compositions exhibit variations in properties because of different lattice symmetries. Thus, if stacked together into multilayers, polymorphs may work as an alternative approach to the sequential deposition of layers with different chemical compositions. However, selective polymorph crystallization during conventional thin film synthesis is not trivial; e.g. opting for step-like changes of temperature and/or pressure correlated with switching from one polymorph to another during synthesis is tricky, since it may cause degradation of the structural quality. In the present work, applying the disorder-induced ordering approach we fabricated such multilayered polymorph structures using ion beams. We show that during ion irradiation of gallium oxide, the dynamic annealing of disorder may be tuned towards self-assembling of several polymorph interfaces, consistently with theoretical modelling. Specifically, we demonstrated multilayers with two polymorph interface repetitions obtained in one ion beam assisted fabrication step. Importantly, single crystal structure of the polymorphs was maintained in between interfaces exhibiting repeatable crystallographic relationships, correlating with optical cross-sectional maps. This data paves the way for enhancing functionalities in materials with not previously thought capabilities of ion beam technology.