Spatially resolved dark count rate of SiPMs

E Engelmann,E Popova,S Vinogradov

doi:10.1140/epjc/s10052-018-6454-0

Abstract

In this work we present a novel method for the spatially resolved characterization of crystal defects in SiPMs. The contribution of crystal defects to the DCR is evaluated by exploiting the effect of “hot carrier luminescence” (HCL), which is light that is emitted during the Geiger mode operation of avalanche photodiodes (SiPM micro-cells). Spatially confined regions with an enhanced light emission intensity (hotspots) are identified within the active areas of SiPM micro-cells. By correlating the detected light intensity and the DCR, a significant contribution of up to 56% of the DCR can be attributed to less than 5% of the micro-cells. The analysis of the temperature dependence of the emitted light identifies the Shockley-Read-Hall-Generation to be the dominant mechanism responsible for the occurrence of hotspots. The motivation of this work is to generate a deeper understanding of the origin of hotspots in order to suppress their contribution to the DCR of SiPMs.

Highlights

Mapping of the dark count rate (DC R) for every microcell of a digital Silicon Photomultiplier (SiPM) was reported by Frach et al [5]
In this work we present a method for a spatially resolved characterization of the DC R of SiPMs by detecting light emitted by hot carrier luminescence (HCL) with a low-light level CCD camera
In order to adjust the temperature of the device, the SiPM is mounted onto a thermo-electric cooler inside an evacuated TO-8 package

Summary

Introduction

Mapping of the dark count rate (DC R) for every microcell of a digital SiPM was reported by Frach et al [5]. The group showed that excluding 5% of the most active micro-cells results in a reduction of the dark count rate by up to an order of magnitude. Their results did not provide information on the origin of micro-cells with a higher DC R. Regions with a significantly enhanced light intensity (hotspots) are evident within the active areas of certain SiPM micro-cells. Micro-cells with a hotspot contribute with up to 7% to the total DC R, while a contribution of approximately 0.45% is expected on average

Objectives

Methods

Results

Conclusion