In this paper, we give an overview of the main properties and technological implementation of densely packed Single-photon Avalanche Diode arrays, which are commonly known as Silicon ...Photomultipliers, or SiPMs. These detectors feature high internal gain, single-photon sensitivity, a high Photon Detection Efficiency, proportional response to weak and fast light flashes, excellent timing resolution, low bias voltage, ruggedness and insensitivity to magnetic field. They compare favorably to the traditional Photomultiplier Tube in several applications. In this overview paper, we go through the SPAD/SiPM theory of operation, the modern SiPM implementations and the typical technological options to build the sensor. This is done in conjunction with the description of the main SiPM parameters, such as the Photon Detection Efficiency, the electrical properties, the primary and correlated noise sources and the Single Photon Time Resolution.
Different applications require different customizations of silicon photomultiplier (SiPM) technology. We present a review on the latest SiPM technologies developed at Fondazione Bruno Kessler (FBK, ...Trento), characterized by a peak detection efficiency in the near-UV and customized according to the needs of different applications. Original near-UV sensitive, high-density SiPMs (NUV-HD), optimized for Positron Emission Tomography (PET) application, feature peak photon detection efficiency (PDE) of 63% at 420 nm with a 35 um cell size and a dark count rate (DCR) of 100 kHz/mm². Correlated noise probability is around 25% at a PDE of 50% at 420 nm. It provides a coincidence resolving time (CRT) of 100 ps FWHM (full width at half maximum) in the detection of 511 keV photons, when used for the readout of LYSO(Ce) scintillator (Cerium-doped lutetium-yttrium oxyorthosilicate) and down to 75 ps FWHM with LSO(Ce:Ca) scintillator (Cerium and Calcium-doped lutetium oxyorthosilicate). Starting from this technology, we developed three variants, optimized according to different sets of specifications. NUV-HD⁻LowCT features a 60% reduction of direct crosstalk probability, for applications such as Cherenkov telescope array (CTA). NUV-HD⁻Cryo was optimized for cryogenic operation and for large photosensitive areas. The reference application, in this case, is the readout of liquid, noble-gases scintillators, such as liquid Argon. Measurements at 77 K showed a remarkably low value of the DCR of a few mHz/mm². Finally, vacuum-UV (VUV)-HD features an increased sensitivity to VUV light, aiming at direct detection of photons below 200 nm. PDE in excess of 20% at 175 nm was measured in liquid Xenon. In the paper, we discuss the specifications on the SiPM related to different types of applications, the SiPM design challenges and process optimizations, and the results from the experimental characterization of the different, NUV-sensitive technologies developed at FBK.
Bismuth germanate (BGO) was a very attractive scintillator in early-generation positron emission tomography (PET) scanners. However, the major disadvantages of BGO are lower light yield and longer ...rise and decay time compared to currently popular scintillators such as LSO and LYSO. This results in poorer coincidence timing resolution and it has generally been assumed that BGO is not a suitable scintillator for time-of-flight (TOF) PET applications. However, when a 511 keV photon interacts in a scintillator, a number of Cerenkov photons are produced promptly by energetic electrons released by photoelectric or Compton interactions. If these prompt photons can be captured, they could provide a better timing trigger for PET. Since BGO has a high refractive index (increasing the Cerenkov light yield) and excellent optical transparency down to 320 nm (Cerenkov light yield is higher at shorter wavelengths), we hypothesized that the coincidence timing resolution of BGO can be significantly improved by efficient detection of the Cerenkov photons. However, since the number of Cerenkov photons is far less than the number of scintillation photons, and they are more abundant in the UV and blue part of the spectrum, photosensors need to have high UV/blue sensitivity, fast temporal response, and very low noise in order to trigger on the faint Cerenkov signal. In this respect, NUV-HD silicon photomultipliers (SiPMs) (FBK, Trento, Italy) are an excellent fit for our approach. In this study, coincidence events were measured using BGO crystals coupled with NUV-HD SiPMs. The existence and influence of Cerenkov photons on the timing measurements were studied using different configurations to exploit the directionality of the Cerenkov emissions. Coincidence resolving time values (FWHM) of ~270 ps from 2 × 3 × 2 mm
BGO crystals and ~560 ps from 3 × 3 × 20 mm
BGO crystals were obtained. To our knowledge, these are the best coincidence resolving time values reported for BGO to date. With these values, BGO can be considered as a relevant scintillator for TOF PET scanners, especially if photodetectors with even better near UV/blue response can be developed to further improve the efficiency of Cerenkov light detection.
Performance of NUV-HD Silicon Photomultiplier Technology Piemonte, Claudio; Acerbi, Fabio; Ferri, Alessandro ...
IEEE transactions on electron devices,
2016-March, 2016-3-00, 20160301, Letnik:
63, Številka:
3
Journal Article
Recenzirano
In this paper, we present the full characterization of a new high-density (HD) cell silicon photomultiplier (SiPM) technology for ultraviolet (UV) and blue light detection, named near UV HD SiPM. ...Thanks to an optimized border region around each cell, we were able to develop devices having a very high detection efficiency and, at the same time, a high dynamic range. We produced SiPMs with a square cell pitch of 15, 20, 25, and 30 μm featuring a peak efficiency in the violet region ranging from 40% to 55%, according to the cell size. We tested this technology for time-of-flight positron emission tomography. Using two 4 × 4 mm 2 SiPMs with a 25 × 25 μm 2 cell pitch coupled to 3 × 3 × 5 mm 3 LYSO scintillators, we reached for the first time 100-ps full-width at half-maximum coincidence time resolution. This result was independent of the temperature in a range from 20 °C to -20 °C. At the same time, thanks to the high dynamic range and low correlated noise, we obtained an energy resolution lower than 9% for 511-keV γ-rays.
This paper reports on the electrical characterization of the first prototypes of Geiger-Mode Avalanche Photodiodes (GM-APDs) and Silicon Photomultipliers (SiPMs) produced at ITC-irst, Trento. Both ...static and functional measurements have been performed in dark condition. The static tests, consisting in reverse and forward IV measurements, have been performed on 20GM-APDs and 90 SiPMs. The breakdown voltage, the quenching resistance value and the current level have been proved to be very uniform. On the other hand, the analysis of the dark signals allowed the extraction of important properties such as the dark count rate, the gain, the after-pulse and optical cross-talk (in case of the SiPMs) rates. These parameters have been evaluated as a function of the bias voltage, showing trends perfectly compatible with the theory of the device
In this paper, we present the results of the characterization of the first high-density (HD) cell silicon photomultipliers produced at FBK. The most advanced prototype manufactured with this ...technology has a cell size of 15 × 15 μm 2 featuring a nominal fill factor of 48%. To reach this high area coverage, we developed a new border structure to confine the high electric-field region of each single-photon avalanche diode. The measured detection efficiency approaches 30% in the green part of the light spectrum and it is above 20% from 400 to 650 nm. At these efficiency values, the correlated noise is very low, giving an excess charge factor below 1.1. We coupled a 2 × 2 × 10- mm 3 LYSO scintillator crystal to a 2.2 × 2.2- mm 2 silicon photomultiplier, obtaining very promising results for PET application: energy resolution of less than 11% full-width at half maximum (FWHM) with negligible loss of linearity and coincidence resolving time of 200-ps FWHM at 20°C.
This paper presents the performance, in terms of energy and timing resolution, of high-density silicon photomultipliers (SiPMs) produced at Fondazione Bruno Kessler for time-of-flight positron ...emission tomography application. The new SiPM technology allows us to produce devices with a small cell size maintaining a high fill factor (FF). The sensors considered in this paper are composed by 30 × 30 μm(2) cells with a FF exceeding 70% to cover a total area of 4 × 4 mm(2). The SiPM performance was evaluated using two types of scintillators (Ce:LYSO and Ce:GaGG) both with a short height (5 mm) in order to minimize the time jitter caused by light propagation in the crystal. With Ce:LYSO, an energy resolution of 9.0% FWHM at 511 keV and a coincidence resolving time (CRT) of 125 ps FWHM were obtained at -20 °C. With Ce:GaGG, an energy resolution of 6.4% FWHM and a CRT of 260 ps FWHM were achieved at the same temperature. The novel SiPM technology, combining a high PDE with a low correlated noise (i.e., crosstalk and afterpulse), allows us to improve the state-of-the-art of energy and timing resolution with both the tested crystals.
High-performance optical power converters (OPCs) enable isolated electrical power and power beaming applications at new wavelengths and higher output powers. Broadcom’s vertical epitaxial ...heterostructure architecture (VEHSA) multi-junction OPCs permit optical-to-electrical conversion at high efficiency and at manageable external loads. This study provides details of how the power outputs have been extended from <1 W to a power class at ~3 W and another class at >20 W. The work also provides details of how the spectral range options have been extended from 800–830 nm to other key laser diode wavelengths such as 960–990 nm and 1500–1600 nm.
A new Silicon Photomultiplier structure for blue light detection Piemonte, Claudio
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2006, Letnik:
568, Številka:
1
Journal Article
Recenzirano
Silicon Photomultipliers are extremely promising devices for those applications requiring the detection of very low-intensity light (down to single photon detection). The major drawback of the ...existing prototypes is the poor detection efficiency, especially at short wavelengths (below 10% in the blue region). In this paper, a new structure aimed at improving this parameter at wavelengths ranging from 400–450
nm is presented. With respect to a conventional structure it allows a maximization of the breakdown initiation probability for a given bias voltage and a reduction of the dead area. The analysis is supported by TCAD simulations.
PDF
