Comparison of characteristics of silicon detectors with multiple guard rings depending on electrode bias

Multiple guard-ring structured silicon detector was designed, fabricated, and its electrical characteristics and radiation detection performance were evaluated depending on the guard ring bias. In this study, the silicon detector was produced on the 675 μm-thick, high-resistivity n-type wafer with two floating guard rings and one voltage applicable guard ring. Applying bias to the guard ring reduced the active region leakage current to less than one-tenth of the unbiased value, achieving leakage current comparable to cryogenic operation. Radiation response was evaluated by alpha sources ( 241 Am, 226 Ra) and gamma sources ( 133 Ba, 241 Am). Without guard ring bias, spurious peaks matching the alpha full energy peak pattern occurred repeatedly, corresponding to the number of floating electrodes. Conversely, when a bias was applied to the guard ring, the active region was electrically shielded by the biased guard ring, causing the interference signal to almost disappear. Instead, a slight peak shift occurred due to the difference in effective electrode area. The energy resolution of this detector did not change significantly depending on whether a voltage was applied to the guard ring. However, in gamma ray measurement, the peak-to-background ratio (PBR) was found to improve overall with the guard ring bias.