Defect Characterization and Gamma Radiation Response of Al/Yb2O3/SiO2/p-Si MOS Structures

This paper reports on the structural evolution and gamma radiation behavior of Al/Yb₂O₃/SiO₂/p-Si MOS capacitors. Structural checks using X-ray diffraction (XRD) verified that post-deposition annealing at 400°C crystallized the Yb₂O₃ layer, resulting in a polycrystalline cubic phase with an average crystallite size of 8.86 nm. Raman spectroscopy further highlighted the development of an interfacial silicate layer, which provides a graded transition effective at limiting interface trap density. Electrical analysis via Capacitance-Voltage (C-V) and Conductance-Voltage (G-V) techniques demonstrated that, unlike conventional SiO₂-based devices, the Yb₂O₃ dielectric exhibits a positive voltage shift under gamma exposure. This behavior indicates an anomalous buildup of net negative charge, attributed to deep electron traps likely associated with the reduction of Yb³⁺ ions. Low device sensitivity was measured to be 1.03 mV/Gy after 160 Gy exposure. Notably, the radiation treatment acted as an annealing mechanism, decreasing interface trap density and suppressing gate leakage current, which suggests that dual Yb₂O₃/SiO₂ stacks can be promising candidates for radiation-hardened devices.