Noise reduction in high-density silicon photomultipliers via passive POCl3 doping on trench

Abstract Deep trench isolation (DTI) is indispensable for suppressing crosstalk and enabling high fill factors in dense silicon photomultipliers (SiPMs). However, plasma-induced sidewall defects create interface states that elevate dark count rate (DCR) and afterpulsing (AP) through generation-recombination and trap-assisted emission. Here, we establish and experimentally validate a quantitative carrier-emission model for DTI sidewall interfaces in SiPMs, linking the emission probability of interface-trapped carriers to the local doping concentration and minority-carrier diffusion length. Conformal POCl 3 doping raises the local Fermi level and fills low-energy interface states, suppressing thermionic hole emission while reducing peripheral field crowding. The optimized devices achieve a ~ 67% reduction in primary DCR and a ~ 42% reduction in AP probability, alongside an activation-energy shift from 0.04 eV to 0.49 eV, evidencing a transition from shallow trap-assisted generation to thermally activated emission. Qualitative infrared-pumped electron counting confirms doping-dependent interface-state filling. This trap-filling strategy decouples dark-noise suppression from photon-detection efficiency, offering a scalable pathway to low-noise, high-density SiPMs for applications requiring high sensitivity and precise timing.