Disorder-induced ordering in gallium oxide polymorphs

TL;DR

This study reveals how radiation-induced disorder can induce phase transitions in gallium oxide, enabling the fabrication of oriented orthorhombic films and discovering a new polymorphic regrowth mode, opening new research avenues.

Contribution

The paper demonstrates that radiation disorder can be harnessed to control polymorphism in gallium oxide, leading to novel film fabrication and polymorphic regrowth methods.

Findings

Amorphization is suppressed by phase transition in gallium oxide.

Oriented orthorhombic films were successfully fabricated.

A new mode of lateral polymorphic regrowth was observed.

Abstract

Polymorphs are common in nature and can be stabilized by applying external pressure in materials. The pressure/strain can also be induced by the gradually accumulated radiation disorder. However, in semiconductors, the radiation disorder accumulation typically results in the amorphization instead of engaging polymorphism. By studying these phenomena in gallium oxide we found that the amorphization may be prominently suppressed by the monoclinic to orthorhombic phase transition. Utilizing this discovery, a highly oriented single-phase orthorhombic film on the top of the monoclinic gallium oxide substrate was fabricated. Exploring this system, a novel mode of a lateral polymorphic regrowth, not previously observed in solids, was detected. In combination, these data envisage a new direction of research on polymorphs in Ga2O3 and, potentially, for similar polymorphic families in other materials.