Non-linear effects in α-Ga2O3 radiation phenomena

The rhombohedral phase of gallium oxide (α-Ga2O3) is of interest because of its highest bandgap among the rest of the Ga2O3 polymorphs, making it particularly attractive in applications. However, even though the ion beam processing is routinely used in device technology, the understanding of radiation phenomena in α-Ga2O3 is not mature. Here, we study non-linear effects for radiation disorder formation in α-Ga2O3 by varying both the defect generation rate and the density of collision cascades, enabled by comparing monoatomic and cluster ion implants, also applying systematic variations of ion fluxes. In particular, we show that the collision cascade density governs the surface amorphization rates, also affected by the ion flux variations. These trends are explained in terms of the non-linear in-cascade and inter-cascade defect interactions occurring during ballistic and dynamic defect annealing stages. As such, these data reveal new physics of the radiation phenomena in α-Ga2O3 and may be applicable for more predictive ion beam processing of α-Ga2O3-based devices.