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Fabrication and characterization of sensitive vertical P-i-N germanium photodiodes as infrared detectors
摘要： Germanium on silicon P-i-N photodetectors fabricated using standard CMOS tools are now successfully used as uncooled detectors in the near-infrared (NIR), which extends from 0.75 to 1.4 μm and in the short-wave infrared (SWIR), which extends from 1.4 to 3 μm. They feature a remarkably high responsivity up to 1550 nm and a low dark current when they are operated at reverse biases. The aim is to achieve a very low dark current density and a high responsivity with a small Germanium photodiode pitch. In this paper we discuss the fabrication and the characterization of vertical P-i-N photodiodes with the epitaxy of Germanium on Silicon. The Germanium epilayer is a 1.3 μm thick Ge ?lm with a bottom Ge layer P-type doped with boron at 1019 cm?3 and a top Ge layer N-type doped with phosphorus at 1020 cm?3. Secondary ion mass spectroscopy was used to assess the doping level of the Phosphorus doped N?+?region. The strain in the Germanium epilayer on Silicon substrate was investigated. It was tensile, with a value around +0.15% from x-ray diffraction (XRD), in good agreement with a +0.12% value from Raman spectroscopy. In this paper, we focus on P-i-N photodiodes with a circular shape and a diameter of 10 μm. Electrical characterizations were performed in dark and under NIR-SWIR radiation (1310 nm, 1550 nm), with very low dark current of 0.45 nA and enhanced photocurrent at ?1 V. The external responsivities were measured at 0.275 and 0.133 A W?1 for 1310 nm and 1550 nm, respectively. Finally, internal quantum ef?ciencies of the fabricated vertical P-i-N photodiodes were extracted at 66% and 52% at 1310 nm and 1550 nm, respectively, in good agreement with TCAD simulations. Finally, a measurement of the noise in dark conditions is presented.
关键词： infrared detectors,photodiodes,strain,germanium
更新于2025-09-23 15:19:57
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CVD preparation of vertical graphene nanowalls/VO2 (B) composite films with superior thermal sensitivity in uncooled infrared detector
摘要： Vanadium dioxide with superior thermal sensitivity is one of the most preferred materials used in microbolometer, and the B phase of VO2 is particularly prominent. However, conventional VO2 (B) undergoes low temperature-coefficient of resistance (TCR) values and large resistances. In this paper, simple controllable composite films of vertical graphene nanowalls/VO2 (B) (i.e., VGNWs/VO2 (B)) with a suitable square resistance (12.98 k?) and a better temperature-coefficient of resistance (TCR) (-3.2 %/K) were prepared via low pressure chemical vapor deposition. The VGNWs can provide a fast channel for electron transport and enhance the conductivity of VO2 (B). This preparation method can provide a low cost, facile and simple pathway for the design and fabrication of high performance VO2 (B) thin films with superior electrical properties for its application in uncooled infrared detectors.
关键词： Chemical vapor deposition,VO2 (B) films,Vertical graphene nanowalls,Uncooled infrared detectors
更新于2025-09-23 15:19:57
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Structural and optoelectronic characterization of Cu2CoSnS4 quaternary functional photodetectors
摘要： Al/p-Si/Cu2CoSnS4/Al quaternary functional semiconductor photodetectors showing solar detector properties were produced via sol-gel method. SEM, EDS and XRD techniques were used in the confirmation of the chemical composition of the photodiodes where nanoparticle like characteristics of Cu2CoSnS4 was seen. UV-vis spectroscopy was used in the investigation of optoelectronic characteristics. It was seen that photodiodes have a high absorption rate with minimum reflectance, bandgap energy was calculated as 1.19 eV. Current – time and current – voltage characteristics of the photodiodes revealed that photodiodes are sensitive to daylight; photodiodes present rectifying characteristics. Thermionic emission theory was used in the calculation of barrier height, ideality factor, photoresponse, photosensitivity, and linear dynamic rate characteristics. Capacitance – voltage, conductance – voltage, corrective capacitance – voltage, corrective conductance – voltage graphs were used to investigate the electrical properties of the Al/p-Si/Cu2CoSnS4/Al photodiodes. The electrical characteristics of the photodiodes reflect frequency dependent characteristics. Such a behaviour was found to be an indication of the existence of interface states. The density of interface (Dit) calculations revealed that the density of interface states strongly depends on AC signal frequency where diminished Dit was seen for increased signal frequency.
关键词： photodetector,photoresponse,Cu2NiSnS4 photodiodes,quaternary functional photodiodes,solar detectors
更新于2025-09-23 15:19:57
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25 Gb/s Directly Modulated Widely Tunable 1.3 ??m Dual Wavelength DFB Laser for THz Communication
摘要： This paper presents a readout integrated circuit called UFXC32k, designed for hybrid pixel semiconductor detectors used in X-ray imaging applications. The UFXC32k integrated circuit, designed in a CMOS 130 nm process, contains about 50 million transistors in the area of 9.64 mm × 20.15 mm. The core of the IC is a matrix of 128 × 256 square-shaped pixels of 75 μm pitch. Each pixel contains a charge sensitive ampli?er, a shaper, two discriminators, and two 14-bit ripple counters. The analog front-end electronics allow processing of sensor signals of both polarities (holes and electrons). The UFXC32k chip is bump-bonded to a pixel silicon sensor and is fully characterized using X-ray radiation. The measured equivalent noise charge for the standard settings is equal to 123 e? rms (for the peaking time of 40 ns) and each pixel dissipates 26 μW. Thanks to the use of trim blocks working in each pixel independently, an effective off- set spread calculated to the input is only 9 e? rms with a gain spread of 2%. The maximum count rate per pixel depends mainly on effective CSA feedback resistance. Dead time in the front end can be set as low as 85 ns. In the continuous readout mode, a user can select the number of bits read out from each pixel to optimize the UFXC32k frame rate, e.g., for a readout of 2 bits/pixel with 200 MHz clock, the frame rate is equal to 23 kHz.
关键词： X-ray imaging,pixel detectors,Matching,single photon counting
更新于2025-09-23 15:19:57
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2D Material-enabled Nanomechanical Bolometer
摘要： We here describe a novel type of long-wavelength radiation detector that measures illumination intensity at room temperature through mechanical transduction. Compared to semiconductor-based bolometers, our nanomechanical detector exhibits low measurement noise and is inherently transparent and flexible. The presented solid-state device is based on a 2D-material film that acts as radiation absorber and detector of mechanical strain at the substrate-absorber interface. Optimization of the 2D material properties and realization of a novel edge-on device geometry combines unprecedented detectivity of 3.34 × 108 cm Hz1/2 W-1 with micrometer-scale spatial resolution. The observed combination of superior performance with the facile and scalable fabrication using only liquid processes shows the potential of the presented detector for future ubiquitous and wearable electronics.
关键词： thermal expansion,MoS2,infrared detectors,graphene,Bolometer
更新于2025-09-23 15:19:57
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Polarization Modulation Instability in All-Normal Dispersion Microstructured Optical Fibers with sub-ns Pumping
摘要： The CMS lead tungstate (PbWO4) electromagnetic calorimeter (ECAL) has successfully achieved its first goal: the discovery of the Higgs boson in 2012. However, longevity studies show that part of the PbWO4 ECAL will not maintain the required performance due to radiation damage incurred at the HL-LHC. The forward region of the detector will suffer the most from radiation damage, and the ECAL Endcaps (EE) will need to be replaced. A scintillator-based option for the EE replacement, Shashlik EE, is presented in the paper. The Shashlik EE is a sampling calorimeter. Tungsten absorber plates are interleaved with scintillator plates (LYSO or CeF3), with quartz and wavelength-shifting (WLS) capillaries optically coupled to the scintillator plates for light output. The Shashlik EE maintains an excellent energy resolution, but compared to the current PbWO4 EE, it is at least five times greater in radiation hardness and has a module size four times smaller allowing four times higher granularity laterally for pileup mitigation and particle identification. Irradiation tests and beam tests results have confirmed the high performance of the Shashlik EE.
关键词： photondetectors,Calorimetry,solid scintillation detectors
更新于2025-09-23 15:19:57
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Vectorial nature in nonlinear multimode interference based ultrafast fiber lasers
摘要： This paper presents a readout integrated circuit called UFXC32k, designed for hybrid pixel semiconductor detectors used in X-ray imaging applications. The UFXC32k integrated circuit, designed in a CMOS 130 nm process, contains about 50 million transistors in the area of 9.64 mm × 20.15 mm. The core of the IC is a matrix of 128 × 256 square-shaped pixels of 75 μm pitch. Each pixel contains a charge sensitive ampli?er, a shaper, two discriminators, and two 14-bit ripple counters. The analog front-end electronics allow processing of sensor signals of both polarities (holes and electrons). The UFXC32k chip is bump-bonded to a pixel silicon sensor and is fully characterized using X-ray radiation. The measured equivalent noise charge for the standard settings is equal to 123 e? rms (for the peaking time of 40 ns) and each pixel dissipates 26 μW. Thanks to the use of trim blocks working in each pixel independently, an effective off-set spread calculated to the input is only 9 e? rms with a gain spread of 2%. The maximum count rate per pixel depends mainly on effective CSA feedback resistance. Dead time in the front end can be set as low as 85 ns. In the continuous readout mode, a user can select the number of bits read out from each pixel to optimize the UFXC32k frame rate, e.g., for a readout of 2 bits/pixel with 200 MHz clock, the frame rate is equal to 23 kHz.
关键词： single photon counting,pixel detectors,Matching,X-ray imaging
更新于2025-09-23 15:19:57
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Temperature sensor based on IR-laser reduced Graphene Oxide
摘要： A simple, cost-effective approach to realize a sensitive temperature sensor based on IR laser reduced graphene oxide (IRLrGO) is reported. The sensor has been obtained by irradiating a graphene oxide (GO) film, placed between two thin glass substrates, with a continuous wave diode laser operating at 970 nm along its entire length. A conductive strip, 13 mm long, 300 μm wide and 7 μm thick, has been generated by moving the GO film on an X-Y translator stage with a given velocity with respect to the fixed laser fiber tip position. The laser treatment has given rise to the GO reduction confirmed by the resistance R measurements as well as from SEM, EDX, ATR-FTIR and Raman analyses. The temperature dependence of the conductive strip resistance has been measured in air from 30?C to 80?C and in high vacuum from 80 K to 300 K. The sample acts as a sensitive and low mass Resistance Temperature Detector (RTD). Such a sensor is biocompatible and requires a very low bias (<1 V). While the performances of the IRLrGO temperature sensor are stable under high vacuum conditions at room temperature, its behavior remains to be studied when it operates under different environmental conditions.
关键词： Interaction of radiation with matter,Materials for solid-state detectors,Fiber Lasers
更新于2025-09-23 15:19:57
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A Data-Driven Home Energy Scheduling Strategy Under the Uncertainty in Photovoltaic Generations
摘要： We report the fabrication of InAs planar avalanche photodiodes (APDs) using Be ion implantation. The planar APDs have a low background doping of 2 × 1014 cm?3 and large depletion widths approaching 8 μm. The thick depletion width enabled a gain of 330 to be achieved at ?26 V at 200 K without inducing a significant tunneling current. No edge breakdown was observed within the APDs. The surface leakage current was found to be low with a gain normalized dark current density of 400 μAcm?2 at ?20 V at 200 K.
关键词： Avalanche photodiodes,ion implantation,infrared detectors
更新于2025-09-23 15:19:57
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Fast and efficient detection of 511 keV photons using Cherenkov light in PbF <sub/>2</sub> crystal, coupled to a MCP-PMT and SAMPIC digitization module
摘要： We study the possibility to use the Cherenkov light for the e?cient detection of 511 keV photons with the goal to use it in TOF-PET. We designed and tested two detection modules consisting of PbF2 crystals attached to Planacon MCP-PMT XP85012. Ampli?ed PMT signals are digitized by the SAMPIC module with high readout rate, up to 105 events/s, and a negligible contribution to the time resolution, below 20 ps (FWHM). We developed a fast 2D scanning system to calibrate the PMT time response and studied in details the timing characteristics of the Planacon PMT. Using a radioactive 22Na source we measured a detection e?ciency of 24% for 511 keV photons in a 10 mm thick crystal and a coincidence resolving time of 280 ps. We analyzed the main factors limiting the time resolution of the large-surface detection module and proposed solutions to improve it, which will be tested in our future project.
关键词： Photon detectors for UV, visible and IR photons (vacuum) (photomultipliers, HPDs, others),Cherenkov and transition radiation,Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA)
更新于2025-09-23 15:19:57