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Temperature dependence simulation and characterization for InP/InGaAs avalanche photodiodes
摘要： Based on the newly proposed temperature dependent dead space model, the breakdown voltage and bandwidth of InP/InGaAs avalanche photodiode (APD) have been investigated in the temperature range from -50°C to 100°C. It was demonstrated that our proposed model is consistent with the experimental results. Our work may provide a guidance to the design of APDs with controllably low temperature coefficient.
关键词： separate absorption, grading, charge, and multiplication avalanche photodiode (SAGCM APD),optical communication,temperature coefficient,dead space effect
更新于2025-09-23 15:23:52
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Room Temperature Graphene Mid-Infrared Bolometer with a Broad Operational Wavelength Range
摘要： The last decade has witnessed the realization of numerous different types of graphene photodetectors with a strong focus on the visible and near-infrared spectral range, in which various high-performance photodetectors exist based on traditional materials such as silicon and III-V compound semiconductors. However, high-speed mid-infrared photodetection at room-temperature is still an unsolved challenge, despite its importance in applications such as security, sensing, and imaging. Here we address this challenge by demonstrating that high-quality graphene is an ideal high-speed bolometric material for the less-explored yet critical mid-infrared photodetection at room temperature, due to its broadband absorption, small heat capacity, and remarkably large temperature coefficient of resistance (TCR) of up to around 1% per Kelvin, which is comparable to that of commercial bolometric materials. We demonstrate a device based on graphene encapsulated in hexagonal boron nitride (hBN) exhibiting decent extrinsic responsivities of 5.1-1.4 mA/W in 3.4-12 μm wavelength range at room temperature, and further predict a detection bandwidth of at least 47 MHz. Our demonstration lays the foundations for graphene high-speed mid-infrared technologies.
关键词： high-quality graphene,broad wavelength range,scattering channels,Mid-infrared bolometer,temperature coefficient of resistance
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Performance characterization for bifacial photovoltaic modules
摘要： The performance of bifacial photovoltaic modules were characterized. The optical transmittance was measured for front and back side illumination. The temperature coefficients were obtained in order to predict the real power that can be produced in an installation under operating conditions. The internal quantum efficiency distribution was measured to distinguish recombination activity which occurred at the silicon via two-dimensional LBIC method.
关键词： optical transmittance spectra,temperature coefficient,bifacial perc solar cells,quantum efficiency
更新于2025-09-23 15:21:01
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Reactive Pulsed Laser Deposition of Clustered-Type MoSx (x ~ 2, 3, and 4) Films and Their Solid Lubricant Properties at Low Temperature
摘要： We studied the tribological properties of amorphous molybdenum sulfide (MoSx) thin-film coatings during sliding friction in an oxidizing environment at a low temperature (?100 °C). To obtain films with different sulfur contents (x ~ 2, 3, and 4), we used reactive pulsed laser deposition, where laser ablation of the Mo target was performed in H2S at various pressures. The lowest coefficient of friction (0.08) was observed during tribo-testing of the MoS3 coating. This coating had good ductility and low wear; the wear of a steel counterbody was minimal. The MoS2 coating had the best wear resistance, due to the tribo-film adhering well to the coating in the wear track. Tribo-modification of the MoS2 coating, however, caused a higher coefficient of friction (0.16) and the most intensive wear of the counterbody. The MoS4 coating had inferior tribological properties. This study explored the mechanisms of possible tribo-chemical changes and structural rearrangements in MoSx coatings upon contact with a counterbody when exposed to oxygen and water. The properties of the tribo-film and the efficiency of its transfer onto the coating and/or the counterbody largely depended on local atomic packing of the nanoclusters that formed the structure of the amorphous MoSx films.
关键词： wear,molybdenum sulfides,solid lubricants,nanoclusters,reactive pulsed laser deposition,low temperature,coefficient of friction
更新于2025-09-23 15:19:57
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Temperature dependence of potential-induced degraded p-type mono-crystalline silicon photovoltaic cell characteristics
摘要： In this paper, the temperature dependence of the characteristic parameters for a p-type mono-crystalline silicon photovoltaic cell before and after a potential-induced degradation (PID) stress, is measured and compared. It is demonstrated that a 9 h PID stress causes both a drastic decrease in the value of shunt resistance by ～35 times and a decrease in the open-circuit voltage, Voc by ～34%. Consequently the maximum power density, Pmax is decreased by ～62%. The temperature coefficient (TC) of Pmax increases from ?0.459 to ?0.330 caused by a 0 to 3 h PID stress and then decreases to ?0.471%/°C caused by a 3 to 9 h PID stress. Before PID stress, the TC of Pmax was determined mainly by the TC of Voc. However, after PID stress, the TC of Pmax was determined both by the TCs of Voc as well as by the fill factor. ? 2019 The Japan Society of Applied Physics
关键词： maximum power density,photovoltaic cell,temperature coefficient,open-circuit voltage,potential-induced degradation,shunt resistance,temperature dependence
更新于2025-09-19 17:13:59
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Unusual Bimodal Photovoltaic Performance of Perovskite Solar Cells at Real-World Operating Temperatures
摘要： A deep understanding of environmental effects on perovskite solar cell (PSC) performance is highly desirable for further progress towards large-scale deployment of this technology. We investigate the operation of PSCs in the temperature range (15?50 C) and report an unusual bimodal behavior in photovoltaic (PV) performance, with positive and negative temperature coefficients (TCs) below and above room temperature (RT), respectively. Furthermore, the performance metrics exhibit hysteresis, as their values depend on whether the measurements are made during the heating or cooling stages of the experiment. Conventional semiconductor solar cells, in contrast, exhibit a monotonic and non-hysteretic performance decline in this temperature range. The variations in power conversion efficiency primarily follow changes in open-circuit voltage and fill factor. Photoluminescence data suggest that the performance variations below RT are accompanied by a reduction in defect-related traps in the perovskite absorber and a drop in interfacial built-in potential at the perovskite/transport layer interface. The behavior above RT follows the conventional trend and can hence be explained by charge-phonon interactions. Our findings offer significant insight into the salient PV properties and photophysics of perovskite materials that define their performance in the real-world operating temperature range.
关键词： charge-phonon coupling,temperature-dependent hysteresis,Perovskite solar cells,Temperature coefficient
更新于2025-09-19 17:13:59
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[IEEE 2019 16th International Conference on Quality in Research (QIR): International Symposium on Electrical and Computer Engineering - Padang, Indonesia (2019.7.22-2019.7.24)] 2019 16th International Conference on Quality in Research (QIR): International Symposium on Electrical and Computer Engineering - Room-Temperature Terahertz Antenna-Coupled Microbolometers with Titanium Thermistor and Heater
摘要： High-detectivity room-temperature terahertz (THz) detectors are expected to be utilized in spectroscopy and imaging for such applications as nondestructive inspection for safety, construction, noninvasive examination for medicine and pharmacy. We have studied THz antenna-coupled bolometers with titanium (Ti) thermistor and heater fabricated on a high-resistivity silicon (Si) substrate with MEMS structures in order to develop uncooled high-performance sensors. In this paper, we report the study on design, electromagnetic (EM) and thermal simulation, fabrication, experiment of THz-wave measurement, and evaluation of performance for single-detector devices, by which large THz array detectors are easily developed. We have achieved good performance as low noise-equivalent power (NEP) of the orders of 10-11 W/Hz1/2 and response frequency of 5.5 kHz by studying a Ti thermistor with thin meander line for the THz antenna-coupled bolometer.
关键词： nondestructive,terahertz (THz),meander line,sensing,thermistor,noise equivalent power (NEP),temperature coefficient of resistance (TCR),responsivity,bolometer,room temperature,uncooled,detector,array
更新于2025-09-16 10:30:52
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Investigation of datasheet provided temperature coefficients of photovoltaic modules under various sky profiles at the field by applying a new validation procedure
摘要： In this study, datasheet provided temperature coefficients of commercially available photovoltaic modules were investigated by taking into account the actual performance parameters (output peak power, short-circuit current and open-circuit current) under different sky profiles (clear, partly cloudy and cloudy) at field by introducing a new validation procedure. This procedure is based on two cases. The first case covers irradiation and temperature whereas the second case covers only irradiation by neglecting the temperature coefficient parts in the actual performance parameters calculation. The actual performance parameters of mono crystalline silicon and cupper indium gallium selenide photovoltaic modules were measured under different sky profiles at field and calculated for considered cases. Measured and calculated results were compared by using the root mean square error and the relative mean error tools. It has been founded that temperature coefficients of commercially available photovoltaic modules could deviate from their datasheet provided values under cloudy sky profile at field. As a result of this, it has been concluded that users should take into account sky profiles at the site where photovoltaic modules are going to be deployed in order to calculate the actual performance parameters and the output energy accurately.
关键词： short-circuit current,output peak power,photovoltaic module,electrical output,open-circuit voltage,temperature coefficient
更新于2025-09-16 10:30:52
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Can Mobility Negative Temperature Coefficient Be Reconciled with the Hopping Character of Transport in Conducting Polymers?
摘要： Poly(3,4-ethylenedioxythiophene) (PEDOT) is a conducting polymer that is used in a wide range of applications such as electronics, optoelectronics and bioelectronics, where the fundamental understanding of the charge transport, and in particular of the electrical conductivity σ, is a prerequisite to develop high performance devices. There are many reports in the literature where the conductivity of archetypical conducting polymer PEDOT doped with Tosylate (PEDOT:TOS) exhibits a negative temperature coefficient, dσ/dT < 0, which is strikingly different from the activated-type behavior with dσ/dT > 0 commonly observed in most conducting polymers. This unusual temperature dependence was attributed to the transition from the photon-assisted hopping to the metallic behavior, which is however difficult to rationalize taking into account that this transition occurs at high temperatures. In order to understand the origin of this unusual behavior, a multi-scale mobility calculations in PEDOT:TOS for the model of hopping transport were performed, where changes in the morphology and the density of states (DOS) with the temperature were explicitly taken into account. The morphology was calculated using the Molecular Dynamics simulations, and the hopping rates between the chains were calculated quantum-mechanically following the Miller-Abrahams formalism. Our results reproduce the observed negative temperature coefficient, where however the percolation analysis shows that this behavior mainly arises because of the changes in morphology upon heating when the system becomes less ordered. This results in a less efficient π-π stacking and hence lower mobility in the system. We therefore conclude that experimentally observed negative mobility temperature coefficient in conducting polymers at high temperatures is consistent with the hopping transport, and does not necessarily reflect the transition to a metallic band-like transport. Based on our multi-scale modeling we introduce a simple Gaussian Disorder Model for the efficient mobility calculations, where the DOS broadening is a function of the temperature, and where the transfer integrals distribution is a bimodal distribution evolving with temperature.
关键词： PEDOT,Band transport,Hopping transport,Negative temperature coefficient,Electrical mobility,Multiscale calculation
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Cooled Silicon-On-Insulator Diode Thermometer: Toward THz Passive Imaging
摘要： Terahertz passive imaging requires high sensitivity detectors, with Minimum Detectable Power (MDP) under the picowatt range. An antenna-coupled cooled microbolometer, incorporating a lateral PiN-like diode as thermometer, could represent a solution. In a first step, such diode performances have to be investigated, especially the temperature coefficient of current (TCC) and the low frequency noise. Prototypes were fabricated on Silicon-On-Insulator (SOI) 4” wafers with 50-nm active silicon layer. I-V and noise measurements down to 81K were useful to derive the electrical MDP of the future bolometer, already reaching 6.6 pW at 10 frames per second.
关键词： low frequency noise,microbolometer,Minimum Detectable Power,PiN diode,temperature coefficient of current,Silicon-On-Insulator,Terahertz passive imaging
更新于2025-09-12 10:27:22