Investigating Radiation-Induced Crystalline Defects in AlGaN

GaN, AlN, and their ternary alloys (AlxGa1-xN) represent a significant class of wide-bandgap semiconductors widely utilized in high-performance applications such as radiation-hard electronics, optoelectronic devices, and power electronics. These materials exhibit exceptional properties, including thermal stability, high breakdown voltage, and resistance to radiation, making them key candidates for use in harsh environments, such as space and nuclear reactors. Understanding the impact of irradiation on these semiconductors is critical for improving their reliability and performance in such demanding applications.
In this study, both atomistic modeling and experimental techniques are employed to investigate the effects of radiation-induced defects in GaN, AlN, and their alloys. The focus is on defect formation mechanisms caused by different types of irradiation, including low-energy recoil events (on the order of tens of keV or less) and high-energy swift ion impacts, which are typical in space environments.
For low-energy recoils, we conducted a comprehensive analysis of defect formation across different compositions of AlxGa1-xN alloys. This analysis highlights how varying aluminum content influences radiation tolerance and defect evolution, including the formation of vacancies, interstitials, and defect clusters. The simulation results align well with experimental data at temperatures up to room temperature. Our results show that alloy composition plays a key role in defect production and microstructural evolution. As aluminum content increases, the production of point defects from individual recoil events decreases. However, at higher radiation doses, cumulative effects lead to the formation of extended defects, such as dislocation loops and larger defect clusters in Al-rich alloys. Notably, the alloy with 25% aluminum content (Al0.25Ga0.75N) showed the least overall radiation damage, suggesting an alloying strategy for reducing radiation effects through moderate aluminum incorporation.
The study further explores the structural changes in GaN and AlN resulting from swift heavy ion irradiation, which is characteristic of space radiation environments. It is found that this high-energy irradiation induces complex structural alterations such as cavity formation in GaN while being much less severe in AlN. Combining molecular dynamics simulations, a mechanistic understanding of the microstructural changes in GaN and AlN is provided.
Overall, this work provides insights into the defect dynamics and radiation response of GaN, AlN, and their alloys, contributing to the development of more resilient semiconductor devices for radiation-intensive applications.