Sb-Doped Substrates for Low-Noise Silicon Photomultipliers

Suppressing dark noise in silicon photomultipliers (SiPMs) remains highly challenging because Geiger-mode operation inherently leads to high dark count rates (DCR). Although epitaxial silicon layers grown on heavily doped substrates are widely employed, high-temperature epitaxial processing often induces dopant autodoping and the formation of interface states, which significantly exacerbate noise. In this work, we demonstrate that SiPMs fabricated on antimony (Sb)-doped substrates exhibit approximately 20% lower DCR, up to 40% higher photon detection efficiency, and about 15% improvement in single-photon timing resolution at an excess bias of 8 V, compared with their arsenic (As)-doped counterparts. These performance enhancements are attributed to the larger covalent radius and higher diffusion activation energy of Sb, which effectively suppress autodoping and minimize interface-state formation at the epitaxial–substrate boundary, thereby enabling low-noise, high-precision SiPM operation.