Ion Irradiation Induced Phase Transformation in -Ga₂O₃ Through In Situ Ion Irradiation in a TEM

This research reports the effects of radiation damage and temperature on the stability and semiconductor properties of gallium oxide (Ga₂O₃). Along with considering how the semiconductor properties (electrical and optical) are affected, it is important to understand the irradiation response of a Ga2O3 single crystal in terms of its structure using in-situ irradiation in a TEM. Characterizing the phases present at different irradiation doses through the use of electron diffraction can reveal transition doses and, in turn, phase stability. This is all the more important than Ga2O3 is known to be polymorphic that can be present in six different phases: <i>α, β, γ, δ, ε</i> and <i>κ. </i>Monitoring radiation effects in terms of possible phase changes and radiation damage (black dot and loop formation) is critical to understanding the possible changes in physical properties. In the literature, a phase transformation from <i>β to κ</i> was reported in bulk Ga2O3 at room temperature for a given dose [1]. Later, it was reported that the actual phase forming was <i>γ and not </i>κ. In order to bring more light onto this irradiation induced phase transformation, a systematic study is needed not only to further investigate the mechanisms of the phase transformation in Ga2O3 but also the effect of temperature in a timely manner (which has not been reported in the literature). For that matter, in situ irradiations in a TEM were done using 1 MeV Kr ion irradiation of Ga2O3 TEM foils processed through Focused Ion Beam Lift out method. The gallium oxides samples were grown either by Czochralski (CZ) or Edge-defined Film-Fed Growth (FFG) techniques. Detailed Diffraction Pattern analysis was performed as a function of irradiation dose, which brought more insight onto the phase transformation and temperature dependence, which will be reported in this presentation. The experiments showed that phase transformation does not require implantation of ions as the ions travel through the foil in our case. The possible mechanism will be discussed in this presentation.<br/><br/>This work was supported as part of Nuclear Science and Security Consortium (NSSC) (DE-NA0003996) and experiments at the IVEM, an NSUF facility, were made possible thanks to DOE through the NSUF award 20-19163.