Characterization of silicon photomultipliers at National Nano-Fab Center for PET-MR

Abstract

The silicon photomultipliers (SiPMs) were fabricated for magnetic resonance compatible positron emission tomography (PET) applications using customized CMOS processes at National NanoFab Center. Each micro-cell consists of a shallow n+/p well junction on a p-type epitaxial wafer and passive quenching circuit was applied. The size of the SiPM is 3 × 3 mm(2) and the pitch of each micro-cell is 65 μm. In this work, several thousands of SiPMs were packaged and tested to build a PET ring detector which has a 60 mm axial and 390 mm radial field of view. I-V characteristics of the SiPMs are shown good uniformity and breakdown voltage is around 20 V. The photon detection efficiency was measured via photon counting method and the maximum value was recorded as 16% at 470 nm. The gamma ray spectrum of a Ge-68 isotope showed nearly 10% energy resolution at 511 keV with a 3 × 3 × 20 mm(3) LYSO crystal.

Optimization of a guard ring structure in Geiger-mode avalanche photodiodes fabricated at National NanoFab Center

“…G-APDs with GR test patterns were fabricated at NNFC via a customized CMOS process [7]. Each structure was defined with an abrupt n + /p junction on a p-type epitaxial layer wafer with a passive poly-silicon quenching resistor.…”

Development of P-on-N silicon photomultiplier prototype for blue light detection

“…In the past, SiPMs based on N-on-P structure have been developed at Korea Advanced Institute of Science and technology (KAIST) with a collaboration of National Nanofab Center (NNFC) for PET-MR applications [7]. However, N-on-P structure was not the optimal choice for common PET systems because they exhibit the maximum sensitivity in green light range whereas LYSO crystals show the maximum emission at 420 nm.…”