Effect of Gamma Radiation on Static DC, Reliability, and RF Performance of Submicron GaN-on-Si RF MIS-HEMTs With In Situ SiN

This work demonstrates the synergistic effects of 100 kGy gamma irradiation on the electrical and reliability performance of submicron GaN-on-Si RF MIS-HEMTs with in situ SiN. The results reveal a significant reduction in contact and sheet resistance attributed to annealing effects and defect restructuring, as characterized by TLM measurements. These structural changes contribute to improvements in drain current and transconductance while maintaining a stable threshold voltage, as evidenced by input and output characteristics. Furthermore, the reliability characteristics, as measured by gate-lag/drain-lag measurements, confirm a reduction in trapping sites within the gate and gate-drain access regions, leading to improved ON-resistance stability post-gamma irradiation. A decrease in off-state leakage current and improved degradation voltage further supports the reduction of native defects, as confirmed by the gate and drain step stress measurements. The study also analyzes the RF performance using S-parameters and load-pull measurements, demonstrating improvements in small and large signal RF parameters driven by increased drain current and reduced trapped carriers. Collectively, these improvements in $0.3~\mu $ m gate-length GaN-on-Si RF MIS-HEMTs post-irradiation enable the design and fabrication of GaN MIS-HEMTs using the $0.25~\mu $ m industry semiconductor process, making them highly suitable for radiation-prone environments and space applications.