Anisotropic expansion and amorphization of Ga2O3 irradiated with 946 MeV Au ions

The structural response of beta-Ga2O3 to irradiation-induced electronic excitation was investigated. A polycrystalline pellet of this material was irradiated with 946 MeV Au ions and the resulting structural modifications were characterized using in situ X-ray diffraction analysis at various ion fluences, up to 1 x 10(13) cm(-2). Amorphization was induced, with the accumulation of the amorphous phase following a single-impact mechanism in which each ion produces an amorphous ion track along its path. Concurrent with this phase transformation, an increase in the unit cell volume of the material was observed and quantified using Rietveld refinement. This unit cell expansion increased as a function of ion fluence before saturating at 1.8%. This effect is attributed to the generation of defects in an ion track shell region surrounding the amorphous track cores. The unit cell parameter increase was highly anisotropic, with no observed expansion in the [010] direction. This may be due to the structure of beta-Ga2O3, which exhibits empty channels of connected interstitial sites oriented in this direction. (C) 2015 Elsevier B.V. All rights reserved.