Ultra-Large Compressive Plasticity of E-GaO Thin Films at the Submicron Scale.

Gallium oxide (GaO) usually fractures in the brittle form, and achieving large plastic deformability to avoid catastrophic failure is in high demand. Here, ε-GaO thin films with columnar crystals and partial unoccupied Ga sites are synthesized, and it is demonstrated that the ε-GaO at the submicron scale can be compressed to an ultra-large plastic strain of 48.5% without cracking. The compressive behavior and related mechanisms are investigated by in situ transmission electron microscope nanomechanical testing combined with atomic-resolution characterizations. The serrated plastic flow and large strain burst are two major deformation forms of ε-GaO during compression, which are attributed to the dislocation nucleation and avalanches, formation of new grains, and amorphization. The ultra-large compressive plasticity of ε-GaO thin films at the submicron scale can inspire new applications of GaO in micro- or nano- electronic and optoelectronic devices, especially those that require impact resistance during processing or service.