Radiation Damage Effects in the UWBG Semiconductors Ga₂O₃ and AlN

Ultra-wide bandgap (UWBG) semiconductors, characterized by their substantial energy bandgaps, exhibit superior critical electric field tolerance, enhanced bond strength, and a propensity for high-power handling and deep ultraviolet operation. These materials demonstrate resilience in elevated temperature and corrosive environments. Nevertheless, the realization of their full potential necessitates addressing specific challenges inherent to each UWBG semiconductor. For instance, β-Ga2O3 suffers from low thermal conductivity, AlGaN encounters lattice mismatch with its growth substrate, and diamond is limited by the availability of only deep-level donors and acceptors. In terms of the effects of radiation exposure on these materials, Ga2O3 is expected to show similar radiation resistance as GaN and SiC, considering their average bond strengths. However, this is not enough to explain the orders of magnitude difference of the relative resistance to radiation damage of these materials compared to GaAs and dynamic annealing of defects is much more effective in Ga2O3. Octahedral gallium monovacancies are the main defects produced under most radiation conditions because of the larger cross-section for interaction compared to oxygen vacancies. Proton irradiation introduces two main paramagnetic defects in Ga2O3, which are stable at room temperature. Charge carrier removal can be explained by Fermi-level pinning far from the conduction band minimum due to gallium interstitials (Gai), vacancies (VGa), and antisites (GaO). With few experimental or simulation studies on single event effects (SEE) in Ga2O3, it is apparent that while other wide bandgap semiconductors like SiC and GaN are robust against displacement damage and total ionizing dose, they display significant vulnerability to single event effects at high Linear Energy Transfer (LET) and at much lower biases than expected. Radiation damage in diamond can lead to the formation of defects, such as vacancies and interstitials, which can degrade its optical and electrical properties, reducing its efficiency for applications like quantum computing and radiation detectors. Radiation damage in high Al content AlGaN alloys can compromise the performance of deep UV LEDs and transistors. In summary, Si typically has a substantially higher carrier removal rate compared to UWBG semiconductors under radiation exposure, making UWBG materials more suitable for applications in harsh radiation environments.