1,720,976 research outputs found
SiPM and readout electronics for the JUNO-TAO Central Detector
No full textThe Taishan Antineutrino Observatory (TAO) is a satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO). TAO consists of a spherical ton-level Gadolinium-doped Liquid Scintillator detector and its main purpose is the precise measurement of the reactor antineutrino spectrum by detection of light produced in (v) over bar (e) + p -> e(+) reaction, as a reference for JUNO. About 4,500 photoelectrons per MeV could be detected by instrumenting the sphere surface (similar to 10 m(2)) with state-of-the-art Silicon PhotoMultipliers (SiPMs), resulting in a sub-percent energy resolution. In this work we present the implemented architecture of the readout electronics based on low-noise, high-speed Front-End Boards (FEBs) connected to a 50 x 50 mm(2) SiPM Hamamatsu tile, composed by 32 SiPM elements of 12 x 6 mm(2) each, divided into two independent output channels. The overall 4,024 FEBs will be supplied through eight custom flanges that have to bring in about 1.5 kW. On the same flanges the 8,048 output signal cables are distributed and routed to the Front-End Controllers (FECs), based on Virtex Ultrascale FPGAs, able to manage up to eight 16-channel ADCs, for a total of 128 channels on a single FEC, with a maximum sampling rate of 250 MHz with 12-bit resolution. A dedicated trigger and data-acquisition system will filter and record occurring events, rejecting dark count events. We report the results of the characterization for the pre-production FEBs batch, following the main figures of merit defined for the experiment, showing single photoelectron resolution better than 13% and dynamic range up to 250 photoelectrons
Colloidal quantum dots for optoelectronic applications: Fundamentals and recent progress
No full textIn this work, we present highlights and major milestones in the field of CQDs, starting from their optical and electronic properties that can be tailored not only by the atomic composition but also by the size, shape, and surface functionalization. We will also touch on CQD synthesis, processing and assembly, emphasizing their flexibility, low cost, low temperature and scalability. We will review recent advances in the design and fabrication of optoelectronic devices based on colloidal semiconductor quantum dots, with emphasis on light emitters, detectors and solar cells. We conclude with a short discussion on the large potentialities of this new class of materials as well as the challenges that must be addressed towards solution-processed functional optoelectronic nanomaterials for their practical applications in various fields
Algorithm-based spectrometer exploiting colloidal PbS quantum dots
No full textIn this work we report on a light analysis system based on narrowband colloidal PbS quantum dot photodetectors. The proposed system is able to identify both the peak wavelength of a quasi-monochromatic radiation and the emission spectrum of an arbitrary light source, in the visible and near infrared spectral range, starting from photocurrent measurements of several photoconductive devices with different spectral responses. We demonstrate the feasibility of our approach, optimizing several system parameters and obtaining a mean error of 5 nm and a maximum resolution of 40 nm as regards the peak wavelength identification and the spectral reconstruction, respectively
Narrowband colloidal quantum dot photodetectors for wavelength measurement applications
No full textHigh performance photodetectors based on colloidal quantum dots have been demonstrated in a wide spectral range spanning from the visible to the mid infrared. Quantum dot photodetectors typically show a low-pass type spectral response with a tunable cutoff wavelength. In this paper, we propose a method for the realization of narrowband photodetectors based on the combination of photoconductors and optical filters, both realized with colloidal PbS quantum dots. We demonstrate that an array of such narrowband photodetectors can be effectively employed for the realization of a compact wavemeter operating in the visible and near-infrared spectral range
Fabrication and characterization of lead sulphide colloidal quantum dot photodetectors for the near infrared
No full textColloidal quantum dots are attracting a lot of interest for the fabrication of optoelectronics devices. In particular, they are suitable for simple, low cost and efficient photodetectors. Here we report on our recent results on lead sulphide colloidal quantum dot photoconductors operating in the near infrared spectral range. We describe the device fabrication process and provide an exhaustive electrical and optical characterization. The photodetectors exhibit a responsivity as high as 46 A/W and specific detectivity of about 1.7·1011 cmHz1/2W-1. Performance are investigated as a function of the voltage bias, device geometry and optical power. An evaluation of the device stability over time was also carried out
PbS Colloidal Quantum Dot Photodetectors operating in the near infrared
Full text linkColloidal quantum dots have recently attracted lot of interest in the fabrication of optoelectronic devices due to their unique optical properties and their simple and low cost fabrication. PbS nanocrystals emerged as the most advanced colloidal material for near infrared photodetectors. In this work we report on the fabrication and characterization of PbS colloidal quantum dot photoconductors. In order to make devices suitable for the monolithic integration with silicon electronics, we propose a simple and low cost process for the fabrication of photodetectors and investigate their operation at very low voltage bias. Our photoconductors feature high responsivity and detectivity at 1.3 μm and 1 V bias with maximum values of 30 A/W and 2·1010 cmHz1/2 W-1, respectively. Detectivity close to 1011 cmHz1/2 W-1 has been obtained resorting to bridge sensor readout. © The Author(s) 2016
Lead sulphide colloidal quantum dots for sensing applications
No full textColloidal Quantum Dots (CQD) have been widely studied for their peculiar optical characteristics such as enhanced optical absorption and tunable absorption spectrum. Many different photodetectors have been proposed but overall performance is still poor from the point of view of the bandwidth and noise performance. Here we propose the employment of a PbS QD photoconductor as an ultra-high sensitivity fire detector, exploiting the outstanding device responsivity at low optical powers. Moreover, we demonstrate the outstanding flexibility of CQD based devices, employing our detectors also as simple pollution gas sensors for NO2 detection
Reducing the drift of colloidal quantum dots photodetectors
No full textColloidal quantum dots represent a breakthrough technology for the development of optical devices, in particular photodetectors. However, the performance of CQDs photodetectors show strong aging phenomena. To solve this problem, we investigate the degradation of NIR photodetectors based on lead sulphide CQDs as a function of time and propose a viable solution to improve their time drift. The approach is based on a polymer or resin deposition for the device passivation. The devices were measured over a long time span and passivated detectors were compared to as grown ones. The results show a reduced drift of the passivated devices
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