Effect on MIM structured parallel quenching capacitor of SiPMs

Abstract

A SiPM is an array of several thousand micro-Geiger-mode APDs (GAPD), and a GAPD generally consists of a PN diode (C(d)), a quenching resistor (R(q)) and any parasitic capacitor (C(q)) in parallel to the quenching resistor. The single-photon pulse shape is determined by a RC decay time, a product of C(total) (C(d)+C(q)) and R(q). A large fraction of current in the long tailed single-photon pulse shape causes Scintillation detectors with SiPM to exhibit a poor timing resolution compared to PMTs, which have very narrow Gaussian single-photon pulse shape. In this paper, a similar to 40fF Metal-Insulator-Metal (MIM) quenching capacitor (C(q-MIM)) parallel to a quenching resistor in a Geiger mode APD is proposed to modify the single-photon pulse shape of a SiPM, in order to improve the timing performance of PET detectors. A single-photon pulse shape with C(q-MIM) has a very fast pulse with a low slow tail, consequently the increasing initial current. (C) 2010 Elsevier B.V. All rights reserved.