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- 2019
- low-temperature electronics
- junction field-effect transistors
- differential operational amplifier
- LTspice environment
- differential stage
- common-mode rejection ratio
- class AB operation
- optimization of analog electronic circuit
- operational amplifier
- LTspice environment
- Electronic Science and Technology
- Don State Technical University
- Southern Federal University
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A new type of structure of optical fiber pressure sensor based on polarization modulation
摘要： In this study, a new type of structure of optical fiber pressure sensor (OFPS) based on polarization modulation is proposed, which selects a high-birefringence fiber (HBF) as the sensing unit to measure the pressure in the fluid medium. The PM-1550-01 fiber produced by NTK Photonics Inc. is evaluated as the sample in our subject. Firstly, the regularities of birefringence variation on the PM-1550-01 followed by the external pressure load and the ambient temperature are analyzed by the finite element method (FEM). The results show that the pressure sensitivity is 2.05 × 10 ? 6 RIU/MPa in the pressure range of 0–100 MPa, and the temperature sensitivity is 7.27 × 10 ? 10 RIU/°C in the temperature range of 0–100 °C. Thus, the pressure-temperature cross-sensitivity is only 0.355 kPa/°C in theory. Secondly, the expression of the output light intensity of the introduced OFPS is deduced based on the principles of polarization interference and phase modulation. Combined with simulation results, the measurement ranges of the sensor can be set and adjusted by the length of the sensing unit. Finally, the proposed OFPS is fabricated and external pressure tests within the range of 0–50 MPa are completed. The results show that the pressure sensitivity is approximately 0.145 dB/MPa in the pressure range of 0–44 MPa. There is a fine consistency between the experimental data and simulation results. In addition, the proposed OFPS has many other advantages, such as small size, simple fabrication process and large measurement range, which make it appropriate to be applied in high-pressure measurement in hostile conditions, e.g., downhole and ocean-bottom.
关键词： Low temperature cross-sensitivity,Polarization modulation,High-birefringence fiber,Optical fiber pressure sensor
更新于2025-09-23 15:21:01
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Growth control and defect passivation toward efficient and low-temperature processed carbon based CsPbIBr2 solar cell
摘要： All-inorganic perovskite CsPbIBr2, has drawn much attention for photovoltaic (PV) application due to its excellent intrinsic stability. However, low device performance and high fabrication temperature still hamper its further progress in flexible application. Herein, Zn substitution has been used to improve the nucleation and growth process for low temperature processed a-phase CsPbIBr2 film. Zn incorporated CsPbIBr2 film exhibits good crystallinity, compact surface morphology and depressed defect state. Low temperature (100 and 160°C) processed carbon based CsPbIBr2 solar cells with improved PV performance have been prepared by using Zn incorporation and room deposited electron transport layer (ETL). A champion efficiency over 9% can be achieved through Zn substitution, which is one of the best values reported for the low temperature processed CsPbIBr2 solar cell without using hole transport layer (HTL). Efficiency over 5% can also be achieved for larger area (1 cm2) rigid and flexible CsPbIBr2 solar cells. These results would provide a new route for preparing high-performance and low temperature processed inorganic perovskite solar cell.
关键词： Carbon electrode,CsPbIBr2,Flexible,Solar cell,Low temperature,Inorganic perovskite
更新于2025-09-23 15:21:01
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Flame Propagation Enhancement by Dielectric Barrier Discharge-Generated Intermediate Species
摘要： The interaction between nonthermal plasma (NTP) and fuel-air mixtures was studied both experimentally and by means of simulations, to elucidate their promotional effect on flame propagation. A promotional effect on flame propagation velocity was experimentally observed by generating a dielectric barrier discharge (DBD), prior to spark plug ignition of an n-heptane mixture in a high-pressure and -temperature environment, using a rapid compression and expansion machine (RCEM). A novel method of concentration calibration for mass-spectral analysis was conducted, to determine the intermediate species in the fuel-air mixtures passing through the DBD plasma. The effect of the intermediate chemical species on flame propagation was examined numerically using the PREMIX code, with the observed species being considered as initial additives in the calculations. The promotional effect was reproduced numerically with the addition of alkyl hydroperoxide to an n-heptane/air mixture; and the higher the temperature and leaner the mixture in the parameter region, the more pronounced was the effect. The promotional behavior was examined using reaction path analysis, on the basis of which enhanced low-temperature oxidation reactions, due to the dissociation of the alkyl hydroperoxide, were determined in pre-flame region.
关键词： dielectric barrier discharge,flame propagation velocity,Plasma-assisted combustion,low-temperature oxidation,isomerization
更新于2025-09-23 15:21:01
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Impact of the implementation of a mesoscopic TiO2 film from a low-temperature method on the performance and degradation of hybrid perovskite solar cells
摘要： High efficiencies of over 20% have been reported in the literature for both planar and mesoscopic hybrid perovskite solar cells, and the preferred configuration for scale-up and commercialization is still a matter of debate. The mesoscopic configuration generally requires a high-temperature processing step, which limits applications and makes the process less cost-effective. We have used low-temperature (LT) processing (≤120 °C) to fabricate high-efficiency planar and mesoscopic TiO2-based hybrid perovskite solar cells with comparable performance, highlighted by a champion LT mesoscopic solar cell with 16.2% efficiency. Photovoltaic efficiencies of 14–16% have been achieved for a mesoporous film thickness ranging from 120 to 480 nm by fine-tuning the precursor solution chemistry. The presence of the LT mesoporous layer improves the preservation of performance under conditions of relative humidity of 60%, especially under illumination. Impedance spectroscopy illustrates a similarity of the locus and kinetics of the recombination processes for both configurations. However, inductive loops usually related to ion migration are observed showing different characteristics between both configurations, pointing to the previously suggested correlation between ion migration and degradation. These results suggest that the beneficial role of a mesoporous TiO2 layer might be the stabilization of harmful defects at the perovskite/electron extraction layer interface, and indicate that interface engineering is critical to achieving improved long-term performance.
关键词： Low temperature TiO2,Perovskite solar cells,Impedance spectroscopy,Interfacial degradation
更新于2025-09-23 15:21:01
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Effect of Ga introduction during the second stage of a coevaporation process of Cu(In,Ga)Se2 layers at low temperature on polyimide substrates
摘要： A proper control of Ga concentration pro?le is mandatory to achieve high e?ciency Cu(In,Ga)Se2 (CIGS) solar cells. At low temperature, deep gradients, detrimental for carriers' di?usion, are obtained when CIGS is deposited with a standard three-stage process: an optimization of the process is needed. In this study, we show the impact of a modify three-stage process on the depth of the notch by introducing Ga ?ux during the second stage from 0 nm/min to 1.1 nm/min. A higher open circuit voltage compensated by a lower short current density is obtained due to higher band gap energy. The surface and the bulk of the CIGS layer was analyzed at the end of the second stage by coupling di?erent characterization techniques: glow discharge optical emission spectroscopy, Raman and X-ray photoelectrons spectroscopy. The presence of binary compounds as well as a Ga enrichment at the end of the second stage are observed when Ga is introduced during the second stage.
关键词： low temperature,X-ray photoelectron spectroscopy,solar cells,Cu(In,Ga)Se2,three-stage process,glow discharge optical emission spectroscopy,Raman spectroscopy,CIGS,Ga concentration pro?le
更新于2025-09-23 15:21:01
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Low-temperature co fired ceramic materials with three different dielectric constants
摘要： A new type of low-temperature co-fired ceramic (LTCC) material with a medium dielectric constant was developed in this study (MK, εr = 20.9). MK can be co-fired with a high-dielectric-constant material (HK, εr = 44.5) and a low-dielectric-constant material (LK, εr = 8.1) previously reported. Glass and ceramic materials similar to HK and LK were used. The compositions of glass and ceramic materials for MK were designed to set the adequate dielectric constant and low-temperature coefficient of the dielectric constant (τεr). The coefficient of thermal expansion (CTE) was matched with those of both the previous materials. MK was confirmed to match well electrically with both the previous materials, had no mechanical defects, and showed minimal inter-diffusion. With the addition of MK, the three types of LTCC material system contribute to the enhancement of the performance and the downsizing of electronic components for high-frequency communication.
关键词： electronic components,high-frequency communication,dielectric constant,co-firing,low-temperature co-fired ceramic
更新于2025-09-23 15:21:01
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Effects of post bonding annealing on GaAs//Si bonding interfaces and its application for sacrificial-layer-etching based multijunction solar cells
摘要： By using the sacrificial layer (SL) etching, GaAs substrates are separated from III–V epi substrate//Si substrate junctions that are made by surface activated bonding (SAB) technologies. The post-bonding low-temperature (300-?C) annealing plays an essential role in achieving a promising (～90%) bonding yield. The effects of the post-bonding annealing are investigated by hard X-ray photoemission spectroscopy and current–voltage measurements of GaAs//Si bonding interfaces. It is found that the concentration of oxygen atoms at interfaces is reduced and the resistance decreases to 1.6–2.1 m??cm2 by the low-temperature annealing. Aluminum fluoride complexes are not observed by X-ray photoelectron spectroscopy on the exposed surfaces of separated GaAs substrates. The roughness average of the surfaces is ≈0.25–0.30 nm. The characteristics of double junction cells fabricated on the GaAs//Si junctions prepared by the SL etching are almost the same as those of cells fabricated by dissolving GaAs substrates after bonding. These results indicate that multijunction cells could be fabricated in a process sequence compatible with reuse of GaAs substrates by combining the SL etching and SAB.
关键词： Sacrificial layer etching,GaAs//Si double junction cells,Surface activated bonding,Low temperature annealing,Epitaxial lift-off
更新于2025-09-23 15:19:57
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Energy band alignment in molybdenum oxide/ Cu(In,Ga)Se2 interface for high efficiency ultrathin Cu(In,Ga)Se2 solar cells from low-temperature growth
摘要： In this work, the molybdenum oxide (MoOx) was employed as a back contact layer to improve the device performance of ultrathin Cu(In,Ga)Se2 (CIGS) solar cells with CIGS absorber synthesized through the low-temperature three-stage co-evaporation process. This contribution focuses on the investigation of the inherent mechanisms and the improved device performance in detail. Our research shows that the energy band of the CIGS/Mo interface can be tuned and the Schottky barrier can be reduced. Compared with the reference sample without MoOx, the back barrier height of the new device with 10 nm MoOx enjoys a significant decrease from 43.83 meV to 15.98 meV because of the improvement of energy band structure. Meanwhile, the results of wxAMPS simulation corroborate that the energy band bends upward in the devices with appropriate thickness of MoOx films, which facilitates the carrier transportation and suppresses the recombination of charge carriers at the MoOx/Cu(In,Ga)Se2 interface. Moreover, the carriers can transport through the MoOx/CIGS interface by tunneling when the MoOx film is thin enough. Finally, by controlling the thicknesses of MoOx films, an efficiency of 10.38 % is achieved in 0.5 μm CIGS solar cells by optimizing the MoOx thickness under the low-temperature three-stage co-evaporation process.
关键词： ultrathin,Cu(In,Ga)Se2,MoOx,low-temperature,energy band
更新于2025-09-23 15:19:57
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Low-Temperature (<40 ?°C) Atmospheric-Pressure Dielectric-Barrier-Discharge-Jet Treatment on Nickel Oxide for pa??ia??n Structure Perovskite Solar Cells
摘要： A scan-mode low-temperature (<40 °C) atmospheric-pressure helium (He) dielectric-barrier discharge jet (DBDjet) is applied to treat nickel oxide (NiO) thin films for p?i?n perovskite solar cells (PSCs). Reactive plasma species help reduce the trap density, improve the transmittance and wettability, and deepen the valence band maximum (VBM) level. A NiO surface with the lower trap density surface of NiO allows better interfacial contact with the MAPbI3 layer and increases the carrier extraction capability. MAPbI3 can better crystallize on a more hydrophilic NiO surface, thereby suppressing charge recombination from the grain boundary and the interface. Further, the deeper VBM allows better band alignment and reduces the probability of nonradiative recombination. NiO treatment using He DBDjet with a scan rate of 0.3 cm/s can improve PSC efficiency from 13.63 to 14.88%.
关键词： atmospheric-pressure,perovskite solar cells,low-temperature,dielectric-barrier-discharge-jet,nickel oxide
更新于2025-09-23 15:19:57
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Plasmonic titanium nitride via atomic layer deposition: A low-temperature route
摘要： To integrate plasmonic devices into industry, it is essential to develop scalable and CMOS compatible plasmonic materials. In this work, we report high plasmonic quality titanium nitride (TiN) on c-plane sapphire grown by plasma-enhanced atomic layer deposition. TiN with low losses, high metallicity, and a plasma frequency below 500 nm was achieved at temperatures less than 500 °C by exploring the effects of chemisorption time, substrate temperature, and plasma exposure time on the material properties. A reduction in chemisorption time mitigates premature precursor decomposition at TS > 375 °C, and a trade-off between reduced impurity concentration and structural degradation caused by plasma bombardment is achieved for 25 s plasma exposure. 85 nm thick TiN films grown at a substrate temperature of 450 °C, compatible with CMOS processes, with 0.5 s chemisorption time and 25 s plasma exposure exhibited a high plasmonic figure of merit (jε0/ε00j) of 2.8 and resistivity of 31 μΩ cm. As a result of the improved quality, subwavelength apertures were fabricated in the TiN thin films and are shown to exhibit extraordinary transmission.
关键词： plasmonic figure of merit,CMOS compatible,low-temperature route,atomic layer deposition,plasmonic titanium nitride
更新于2025-09-23 15:19:57