Researchers have developed a novel technique to significantly reduce noise in high-density silicon photomultipliers (SiPMs). The method involves passive POCl₃ doping in the trench isolation of SiPMs, enabling effective suppression of leakage currents without compromising photon detection efficiency. This advance is crucial for applications requiring high sensitivity and a low rate of spurious events, such as positron emission tomography (PET) and low-light detection in particle physics.

SiPMs are solid-state photon detectors that offer advantages over conventional photomultiplier tubes, such as compactness, robustness, and low operating voltage. However, their performance is limited by dark noise, which increases with integration density and temperature. The proposed technique addresses this issue by modifying the interface between the oxide and silicon in the isolation trenches, where a significant portion of leakage currents originate. POCl₃ doping passivates surface defects, reducing carrier generation and, consequently, dark current.

Experimental results demonstrate a reduction in dark current by up to an order of magnitude compared to untreated devices, while maintaining high photon detection efficiency (PDE) and excellent timing resolution. This improvement in the performance of high-density SiPMs opens new possibilities for the development of more precise medical imaging systems and particle detectors with enhanced sensitivity, driving advancements in fields such as nuclear medicine and gamma-ray astrophysics.