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Photodetectors II - solid state

Session chair: Gundacker , Stefan (RWTH, Germany); Ziemons , Karl (FH Aachen University of Applied Sciences, Faculty of Medical Engineering a. Technomathematics, Juelich, Germany)
Shortcut: N-25
Date: Thursday, 21 October, 2021, 9:15 AM - 11:15 AM
Room: NSS - 2
Session type: NSS Session


Click on an contribution to preview the abstract content.

9:15 AM N-25-01

DarkSide-20k: new technologies for light detection (#591)

L. Consiglio1

1 INFN, LNGS, Assergi (AQ), Italy

On behalf od DarkSide-20k Collaboration


The DarkSide-20k detector will be the next generation dual phase Argon Time Projection Chamber for WIMP dark matter searches aiming at zero instrumental background in an exposure in excess of 100 ton year.  The apparatus will be hosted in the Gran Sasso Underground Laboratory and will be filled with 50 t  active low radioactivity underground Argon suppressed in $^{39}$Ar. Several key technologies are at the basis of the project: the  instrumentation of the Time Projection Chamber  with arrays of  Silicon Photomultipliers configured for the first time in large area tiles readout by a dedicated cryogenic  low noise electronics and assembled into Photo Detector Modules;  the cryogenic transmission of the signals  on  an analog opto transceiver  by means of low radioactivity optical fibers to reduce the cable mass in the cryostat;  the massive production of approximately 10000 tile modules  in the Nuova Officina Assergi, a wide clean room that will host high tech machines for the packaging of the silicon devices and highly qualified  personnel.  We will present the status of these new technologies in DarkSide-20k and the future advancements.

Keywords: Analogue circuits, Detector design, Optical transmission, Photodetection
9:30 AM N-25-02

The DUNE cryogenic Silicon Photomultipliers (#151)

M. Spanu1, 2

1 University, Milano Bicocca, MIlan, Italy
2 INFN, Milano Bicocca, Milan, Italy

on behalf of DUNE collaboration


DUNE is an ambitious long-baseline experiment currently under construction in the US for the study of neutrino oscillation and astroparticle physics. The DUNE far detector consists of four modules based on the Liquid Argon TPC technology and enhanced by a powerful Photon Detection System (PDS) that records the 128 nm scintillation light emitted by the Argon. Given the enormous size of the DUNE Far Detector (10 kton of fiducial mass per module) and the length of the data taking, a dedicated R&D has been carried out to identify photosensors capable to operate reliably at 87 K. These Silicon Photomultipliers (SiPMs) will be coupled with the light trapping and shifting system (X-Arapuca) of the DUNE PDS. In this talk, we present the outcome of the R&D carried out in collaboration with Fondazione Bruno Kessler and Hamamatsu Photonics to design and engineer this novel class of SiPMs. The results include the complete characterization of the sensors (Dark Count Rate, correlated noise, photon detection efficiency, etc.) and the most relevant phenomena that drive the detector behavior at cryogenic temperature (thermal behavior of polysilicon and metallic resistance, signal bandwidth evolution, scaling of DCR, etc.). These results are employed to validate the full electronic chain of the DUNE PDS, which is based on the simultaneous readout of 48 Silicon Photomultipliers per channel with a dedicated cold amplifier. The performance of the entire chain at liquid nitrogen temperature (77 K) will also be detailed.

Keywords: Neutrino detector, photon detection system, SiPMs
9:45 AM N-25-03

Modelisation of light transmission through surfaces with optical coating in Geant4 (#796)

L. Cappellugola1, M. Dupont1, C. - H. Sung2, V. Sharyy2, 3, D. Yvon2, 3, C. Morel1

1 Aix-Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
2 Univ. Paris-Saclay, CEA, Institutde recherche sur les lois Fondamentales de l’Univers, 91191, Gif-su-Yvette, France
3 Université Paris-Saclay, BioMAPs, Service Hospitalier Frédéric Joliot, CEA, CNRS, Inserm, Orsay, France


Surfaces with optical coating may be used to im-prove light transmission between a scintillating crystal and aphotodetector. For the ClearMind project, we develop a detectionmodule made of a PbWO4crystal and a photocathode directlydeposited on thin passivation film coating the crystal face.Scintillation photons will then be transmitted through this thinfilm that has a thickness of the order of scintillation lightwavelength. Interference phenomena and frustrated transmissionbeyond the limit angle have then to be considered. We present themodelisation of light transmission through surfaces with opticalcoating in Geant4, which is achieved by defining a new methodthat provides a transmission probability for optical tracking ofscintillation photons.

Keywords: passivation, thin film, PbWO4, frustrated transmission, optical coating
10:00 AM N-25-04

Performance of black silicon photodiodes for VUV detection in noble liquids (#711)

T. Tsang1

1 Brookhaven National Lab, Upton, United States of America


Black silicon (b-Si) photodiodes are an emerging technology that employs silicon nanostructures to enhance the efficiency of photon detection. Recently, we demonstrated nearly 100% quantum efficiency at <200 nm vacuum ultraviolet (VUV) wavelengths at ambient and in noble liquids, making such devices particularly useful for direct detection of scintillation light in noble liquid detectors. This is important in nuclear science experiments like DarkSide, LUX, XENON, and nEXO, where detection of weak VUV scintillation photons in noble liquids are used to identify rare physics radiation events. Here, we measure the response of b-Si photodiode immerged in LAr and LXe ionization chambers to the scintillation light generated by alpha particles and to establish a guideline for future development on b-Si photodetectors with internal gain to reach single-photon sensitivity.

Keywords: Photon detectors for UV, visible and IR photons, noble gas and liquid detectors
10:15 AM N-25-05

Characterization of Electron-Hole Pair Production by UV Photons in Silicon Photomultipliers (#634)

M. Mahtab1, F. Retiere1, G. Gallina1

1 TRIUMF, Vancouver, British Columbia, Canada


Silicon Photo-Multipliers (SiPMs) have emerged as a compelling photo-sensor solution. In contrast to the widely used Photo-Multipliers Tubes, SiPMs have high single Photon Detection Efficiency (PDE) with low radioactivity. The number of electron-hole pairs produced per photon is an essential parameter for understanding their photon detection efficiency. Previous measurements performed with photodiodes have shown that the number of electron-hole pairs produced per photon increase with photon energy and is higher than unity for wavelengths of below 300. The purpose of this talk is to propose a new experimental method to measure the produced electron-hole pair and, also considering avalanche triggering probability and probability for photoelectron extraction from the surface of the Silicon in the generated current in below and above brake-down regime.

Keywords: Enriched Xenon Observatory experiment (nEXO), Photon Detection Efficiency (PDE), Silicon Photo-Multipliers (SiPMs)
10:30 AM N-25-06

Developments Towards Backside Illuminated Silicon Photomultipliers at Fondazione Bruno Kessler (#399)

A. Mazzi1, G. Paternoster1, A. G. Gola1, F. Acerbi1, P. Bellutti1, G. Borghi1, L. Ferrario1, A. Ficorella1, S. Merzi1, L. Parellada Monreal1

1 Fondazione Bruno Kessler, Sensors and Devices, Trento, Italy


Silicon photomultipliers (SiPMs) are becoming the detector of choice in many fields, including medical instrumentation, industry and scientific experiments. The sensitivity of SiPMs typically covers the entire visible range but, in some applications, sensitivity in the vacuum ultraviolet (VUV) or near infrared (NIR) range is required, posing significant challenges in the technology development and in the device design. Fondazione Bruno Kessler (FBK) is now involved in research programs and instrumental upgrades towards the realization of backside illuminated (BSI) SiPMs. A first demonstration of BSI SiPMs has been recently obtained. A batch of SiPM wafers was thinned to a final thickness of about 10 μm, a few microns in excess compared to the nominal epitaxial layer thickness. An anti-reflective coating was built on the backside and a glass carrier wafer was permanently bonded in order to provide mechanical stability. Although this was a preliminary attempt, mainly intended as a process demonstration, this batch of thinned substrate SiPMs provided an increased photon detection efficiency (PDE) in the NIR range when operated in BSI configuration. The increase in the PDE was of about 50% at 900 nm in devices with metal reflectors, compared to the same front side illuminated technology. Further developments are in progress at FBK towards a BSI SiPM technology optimized for VUV light detection. In several frontier physics experiments, the direct detection of scintillation light produced by liquid noble elements is needed, ranging from 80 nm (He and Ne) to 178 nm (Xe). A BSI SiPM approach could bring several advantages in these fields, such as more flexibility in the entrance window fabrication and the potential of exploiting 3D-integration strategies.

AcknowledgmentThis work was funded by the Italian Ministry “Ministero dello Sviluppo Economico” (MISE) in the framework of the “Important Project of Common European Interest (IPCEI)”.
Keywords: SiPM, Silicon Photomultiplier, 3D-Integration, Backside Illumination, BSI
10:45 AM N-25-07

Amorphous selenium transport layer for ultra-fast, low-noise and sensitive solution-processed nanocrystal photodetectors (#918)

A. Mukherjee1, H. Kannan2, T. Ho1, J. Stavro3, A. Howansky3, N. Nooman1, D. Vasileska4, W. Zhao3, A. Sahu2, A. Goldan3, 1

1 Stony Brook University, Department of Electrical Engineering, Stony Brook, New York, United States of America
2 New York University, Department of Chemical and Biomolecular Engineering, Brooklyn, New York, United States of America
3 Stony Brook University, Department of Radiology, Stony Brook, New York, United States of America
4 Arizona State University, School of Electrical, Computer and Energy Engineering, Tempe, Arizona, United States of America


Nanocrystal quantum dots provide wide spectral tunability and high absorption coefficients owing to quantum confinement and large oscillator strengths, which along with solution processability, allows a facile, low cost and room temperature deposition technique. However, most solution-processed devices are plagued with high dark current densities in the order of  µA/cm2, incomplete passivation, undesirable pinholes, and cracks. This, loss of control over the material morphology reduces film density, consequently lowering absorption per unit length, while simultaneously creating potential electrical shorts through the film and lowering conductivity compared to a continuous film. Thus, our developed vertical-stack photodetectors, uses a solution-processed nanocrystal photoconversion layer coupled to an amorphous selenium wide-bandgap avalanche charge transport layer, in the desired p-i-n fabrication sequence that enables compatibility with active-matrix readout circuitry. Amorphous-selenium detectors have gained significant attention due to their single-carrier hole impact ionization phenomenon (achieved gains ~ 1000), while exhibiting a very low excess noise factor. This chalcogenide glass avalanche transport layer enables the fabrication of low-cost and reliable solution processed nanocrystal devices with high specific detectivity (5x1012 Jones), fast photoresponse with megahertz 3-dB electrical bandwidth (~ 25 Mhz), ultra-low dark current density (~ 10 pA/cm2), low noise current (~ 20 fW/Hz1/2), high linear dynamic range (~ 150 dB) and compatibility with most readout integrated circuits.

Keywords: amorphous selenium, CdSe colloidal quantum-dots, fast photoresponse detector, stable and efficient solution-processed detectors, amorphous charge transport layer
11:00 AM N-25-08

Low-noise, solid-state amorphous selenium photomultipliers using ultra-high-k SrTiO3 hole blocking layer (#1049)

A. Mukherjee1, A. K. Rumaiz3, I. Harding3, D. P. Siddons3, T. Ho1, J. Stavro2, A. Howansky2, W. Zhao2, A. Goldan2, 1

1 Stony Brook University, Department of Electrical Engineering, Stony Brook, New York, United States of America
2 Stony Brook University, Department of Radiology, Stony Brook, New York, United States of America
3 Brookhaven National Laboratory, Upton, New York, United States of America


Although amorphous selenium based solid state avalanche detectors can ideally provide gains comparable to photomultiplier tubes (106), their development has been severely limited by inefficient hole blocking layers, leading to irreversible dielectric breakdown at high electric fields. Thus, understanding of the transport characteristics and physical principles of the blocking layer, including ways to control electrical hot spots and, thereby, the breakdown voltage, is key to improving the performance of avalanche amorphous selenium devices. We propose a low-noise amorphous selenium based solid-state avalanche detector that will use strontium titanate as the high-k dielectric hole-blocking n-layer. The high-k non-insulating strontium titanate layer is required to substantially decrease the electric field at the HBL/high-voltage-metal-electrode interface, thus limiting Schottky injection from the high voltage electrode, in turn preventing Joule heating from crystalizing the amorphous selenium layer.  With this structure, reliable and repeatable impact ionization gain without irreversible breakdown can be achieved. The initial results demonstrate avalanche gains of ~ 150, low-dark current density ~ nA/cm2, and measured ultra-low excess noise factor (less than 2), which, further decreases with an increase in avalanche gain (due to the high phonon scattering/non-ballistic transport of 'hot' holes, thus leading to an internal averaging of the excess noise in amorphous selenium). Finally, we corroborate our observation of decreasing excess noise with an increase in avalanche gain using an in-house multi-scale simulation approach which combines density functional theory and ensemble Monte Carlo simulations.

Keywords: solid-state PMT, amorphous detector, impact ionization gain, low excess noise detector, room temperature detector

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