Effects of Ge ion irradiation on dielectric properties of Si-based PiN diodes

Abstract

The effects of 212 MeV Ge ion irradiation with various irradiation fluences on the dielectric properties of Si-based PiN diodes have been investigated. SRIM simulations demonstrate that Ge ion irradiation primarily induces silicon vacancy (V_Si) defects, leading to the alteration of the silicon lattice structure. The electrical characterization analysis indicates that the impact of Ge ion irradiation on the electrical characteristics of the device is negligible. However, there is a positive correlation between the variation in the dielectric constant (ε’) and the irradiation fluence, wherein ε’ peak shifts towards higher frequencies and the dielectric loss (ε’’) decreases. Raman spectroscopy reveals a significant decrease in the intensity of the main peak at 525 cm⁻¹, accompanied by an increase in the full width at half maximum (FWHM). These observations suggest that Si-Si bonds within the silicon lattice structure might have been broken due to Ge ion irradiation. The deep level transient spectroscopy (DLTS) results also demonstrate a positive correlation between the V₂^(0/−) bulk defects and irradiation fluence. These findings provide important insights into the design of radiation hardened devices, particularly relevant to aerospace and nuclear applications. Furthermore, the correlation between bulk defects and dielectric behaviour provides new avenues for optimizing high-frequency communication systems and energy-efficient semiconductor devices, thus enhancing the relevance of silicon technology in next-generation electronics.