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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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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Liquid Crystal Based SPDT with Adjustable Power Splitting Ratio in LTCC Technology
摘要： This paper presents design and characterisation of a new liquid crystal (LC) based single-pole double-throw (SPDT) with continuously adjustable power splitting ratio in low temperature co-fired ceramic (LTCC) technology. It is designed for a centre frequency of 30 GHz, the fully embedded LC phase including a key component, shifter in stripline topology. The SPDT shows a good matching with |S11| = ?10 dB over a bandwidth of 18 %. It exhibits an insertion loss of 9 dB to 11 dB and an isolation between 22 dB to 32 dB. The continuous tuneability not only allows the selection of each preferred power splitting ratio at the output ports, but also a tuning of the centre frequency. The high insertion loss arises from a certain surface roughness as well as a decreased conductivity of the gold metallisation used.
关键词： single-pole double-throw (SPDT),low temperature co-fired ceramic (LTCC),Liquid crystal
更新于2025-09-04 15:30:14
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Cavity-enhanced absorption sensor for carbon monoxide in a rapid compression machine
摘要： A sensor based on cavity-enhanced absorption spectroscopy (CEAS) was implemented for the first time in a rapid compression machine (RCM) for carbon monoxide concentration measurements. The sensor consisted of a pulsed quantum cascade laser (QCL) coupled to a low-finesse cavity in the RCM using an off-axis alignment. The QCL was tuned near 4.89 μm to probe the P(23) ro-vibrational line of CO. The pulsed mode operation resulted in rapid frequency down-chirp (6.52 cm ?1 / μs) within the pulse as well as a high time resolution (10 μs). The combination of rapid frequency down-chirp and off-axis cavity alignment enabled a near complete suppression of the cavity coupling noise. A CEAS gain factor of 133 was demonstrated in experiments, resulting in a much lower noise-equivalent detection limit than a single-pass arrangement. The sensor thus presents many opportunities for measuring CO formation at low temperatures and for studying kinetics using dilute reactive environments; one such application is demonstrated in this work using dilute n-heptane/air mixtures in the RCM. The formation of CO during first-stage ignition of n-heptane was measured over 802–899 K at a nominal pressure of 10 bar. These conditions correspond to the NTC region of n-heptane and such results provide useful metrics to test and compare the predictions of low-temperature heat release by different kinetic models.
关键词： n-heptane,Low-temperature heat release,Cavity-enhanced absorption spectroscopy,Rapid compression machine,Carbon monoxide
更新于2025-09-04 15:30:14
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Low-Temperature Process for Direct Formation of MoS2 Thin Films on Soda-Lime Glass Substrates
摘要： To obtain molybdenum disulfide (MoS2) patterns without any mechanical problems caused by the transfer process, direct current (DC) sputtering and rapid thermal processing (RTP) were used to form MoS2 instead of the conventional chemical vapor deposition (CVD) process. To form MoS2 on a soda-lime glass substrate at temperatures below 600 °C, MoS2 films were deposited at various DC sputtering powers and annealed at various temperatures from 400 °C to 550 °C. From the scanning electron microscope (SEM) and atomic force microscope (AFM) results, the surface morphologies of the MoS2 films can be observed, depending on the sputtering power and the film thickness. The Raman spectrum results showed that the E1 2g and A1 g mode peaks appeared at approximately 372 cm?1 and 400 cm?1, respectively, and the MoS2 surface was crystallized in the in-plane direction. The X-ray photoelectron spectroscopy (XPS) results showed noticeable S 2p (2p 1/2, 2p 3/2) peaks and Mo 3d (3d 3/2, 3d 5/2) peaks at stable binding energies after RTP at temperatures below 600 °C. The high mobilities and carrier densities of all the MoS2 films can be investigated from the Hall measurements.
关键词： DC Sputtering,Low Temperature,Molybdenum Disulfide (MoS2),Rapid Thermal Processing (RTP),Soda-Lime Glass
更新于2025-09-04 15:30:14
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Fabrication of high fill-factor aspheric microlens array by dose-modulated lithography and low temperature thermal reflow
摘要： A cost-effective fabrication method for high quality and high fill-factor aspheric microlens arrays (MLAs) is developed. In this method, the complex shape of aspheric microlens is pre-modeled via dose modulation in a digital micromirror device (DMD) based maskless projection lithography system. Digital masks for several bottom layers are replaced from circle to hexagon for the purpose of enhancing the fill-factor of MLAs, then a low temperature thermal reflow process is conducted, after which the average surface roughness of microlens is improved to * 0.427 nm while the pre-modeled profile keeps unchanged. Experimental results show that the fabricated aspheric MLAs have almost 100% fill-factor, high shape accuracy and high surface quality. The presented method may provide a promising approach for rapidly fabricating high quality and high fill-factor aspheric microlens in a simple and low-cost way.
关键词： high fill-factor,dose-modulated lithography,aspheric microlens arrays,surface roughness,low temperature thermal reflow
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Waikoloa Village, HI, USA (2018.6.10-2018.6.15)] 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Reactive Silver Ink as a Novel Low-Temperature Metallization: Monitoring Corrosion
摘要： Reactive silver ink (RSI) forms low-resistivity (<5 μΩ?cm) metallization at temperatures below 100 °C –enabling lower resistive losses for thermally sensitive solar cells while drastically reducing Ag usage compared to other low-temperature Ag pastes. However, before adoption of the technology many reliability related questions must be addressed. Ag-based metallizations are susceptible to corrosion by acetic acid formed in encapsulated modules, resulting in increased resistive losses. Here we report on corrosion of three types of metallizations; high-firing-temperature Ag paste (HT Ag Paste), low-temperature Ag paste (LT Ag Paste), and RSI. We develop a method for exposing these metallizations to dilute acetic acid in concentrations comparable to those found in field- and damp heat-exposed modules. We find that HT Ag and RSI are quickly affected by acetic acid exposure after only 24 h. Interestingly, Raman spectroscopy suggests the formation of AgCl or AgCH3COO on HT Ag Paste, dissolution of AgCH3COO from RSI, and LT Ag Paste remains relatively unchanged throughout 2936 h of exposure to diluted acetic acid.
关键词： low temperature metallization,silver usage,metallization,silver,corrosion
更新于2025-09-04 15:30:14
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - A 120 GHz LTCC Packaged Horn Antenna with a Radome and Soft Surface Structure
摘要： A 120 GHz step-profiled horn antenna integrated in low-temperature co-fired ceramic (LTCC) packages with a radome is presented in this paper. As an antenna-in-package (AiP) design, the proposed hollow horn structure is constructed by the cavities with several surrounding fences of vertical metallic vias in multilayer LTCC substrates. In consideration of the practical application, co-design with a thick cylindrical radome attached to the surface of the antenna is also studied. A planar soft surface structure in electromagnetics around the horn antenna is introduced so as to suppress the propagation of surface waves inside the radome and thus improve the gain performance. The simulated results indicate that more than 9 GHz bandwidth of -10 dB return loss and a gain of 12.56 dBi in the radiation direction at 0θ= ? are obtained.
关键词： horn antenna,soft surface,Antenna-in-package (AiP),low-temperature co-fired ceramic (LTCC),radome
更新于2025-09-04 15:30:14
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Low-temperature homoepitaxial growth of two-dimensional antimony superlattices in silicon
摘要： The authors present a low-temperature process for the homoepitaxial growth of antimony superlattices in silicon. The all low-temperature superlattice doping process is compatible as a postfabrication step for device passivation. The authors have used low-temperature molecular beam epitaxy to embed atomically thin (2D), highly concentrated layers of dopant atoms within nanometers of the surface. This process allows for dopant densities on the order of 1013–1014 cm?2 (1020–1021 cm?3); higher than can be achieved with three-dimensional doping techniques. This effort builds on prior work with n-type delta doping; the authors have optimized the growth processes to achieve delta layers with sharp dopant profiles. By transitioning from a standard effusion cell to a valved cracker cell for antimony evaporation, the authors have achieved carrier densities approaching 1021 cm?3 with peak distribution at ～10 ? FWHM for single delta layers. Even at the highest dopant concentrations studied, no deterioration in carrier mobility is observed, suggesting the upper limit for dopant incorporation and activation has not yet been met. The authors will discuss the details related to growth optimization and show results from in situ monitoring by electron diffraction. They will also report on elemental and electrical characterization of the films.
关键词： silicon,molecular beam epitaxy,surface passivation,homoepitaxial growth,delta doping,low-temperature,antimony superlattices
更新于2025-09-04 15:30:14
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Mobility Enhancement in Polycrystalline Silicon Thin Film Transistors due to the Dehydrogenation Mechanism
摘要： We investigated the mechanism of mobility enhancement after the dehydrogenation process in polycrystalline silicon (poly-Si) thin films. The dehydrogenation process was performed by using an in-situ CVD chamber in a N2 ambient or an ex-situ furnace in air ambient. We observed that the dehydrogenated poly-Si in a N2 ambient had a lower oxygen concentration than the dehydrogenated poly-Si annealed in an air ambient. The in-situ dehydrogenation increased the (111) preferred orientation of poly-Si and reduced the oxygen concentration in poly-Si thin films, leading to a reduction of the trap density near the valence band. This phenomenon gave rise to an increase of the field-effect mobility of the poly-Si thin film transistor.
关键词： Low-temperature poly silicon,Crystallization,Dehydrogenation,Thin film transistor
更新于2025-09-04 15:30:14
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Strategic Selection of the Oxygen Source for Low Temperature-Atomic Layer Deposition of Al <sub/>2</sub> O <sub/>3</sub> Thin Film
摘要： The influence of two oxygen source types, H2O and O3, on residual C-related impurities in atomic-layer-deposited (ALD) Al2O3 film is systematically examined. ALD Al2O3 film grown using H2O contains negligible C-related impurities irrespective of growth temperature. However, the C-related impurity in film grown using O3 exhibits strong dependence on growth temperature; only Al carbonate (Al-CO3) is present in film grown at 300 °C, but C-related impurities with lower oxidation states, such as Al-COOH and Al-CHO, appear as the temperature decreases to 150 °C. This suggests that the reactivity of O3 and H2O in the ALD process has a different temperature dependence; from a residual impurity perspective, compared to O3, H2O is a beneficial oxygen source for low temperature processes. Electrical properties, such as charge trapping and gate leakage current, are also examined. For a growth temperature of 300 °C, the film grown using O3 is slightly superior to the film grown using H2O due to its high film density. However, the film grown using H2O demonstrates better electrical characteristics at low growth temperature, 150 °C.
关键词： oxygen source,atomic layer deposition,low temperature process,ozone,water
更新于2025-09-04 15:30:14
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A low temperature approach for photo/cathodoluminescent Gd <sub/>2</sub> O <sub/>2</sub> S:Tb (GOS:Tb) nanophosphors
摘要： Titrating the aqueous solution of equimolar RE(NO3)3 and (NH4)2SO4 with NH4OH to pH~9 at ~4 °C produced an amorphous precursor that yielded phase-pure and well dispersed RE2O2S nanopowder (RE=Gd0.99Tb0.01; GOS:Tb) via a RE2O2SO4 intermediate upon annealing in H2. The powders calcined at the typical temperatures of 700/1200 °C exhibited unimodal size distributions and have the average crystallize sizes of ~17/55 nm, average particle sizes of ~284/420 nm, and specific surface areas of ~14.62/4.53 m2/g (equivalent particle sizes: ~56/180 nm). The 1200 °C product exhibited sharp green luminescence at ~544 nm (FWHM = 2.3 nm; λex = 275 nm), with an absolute quantum yield of ~24.8% and a fluorescence lifetime of ~1.34 ms at room temperature. It was also shown that the powder possesses favorable thermal stability (the activation energy for thermal quenching of luminescence ~0.305 eV) and is stable under electron beam irradiation up to 7 kV and 50 μA. The synthetic technique has the advantages of scalability and favorable dispersion and high chemical/phase purity for GOS powder, which may allow the sintering of scintillation ceramics at lower temperatures.
关键词： low-temperature processing,oxysulfide,GOS,luminescence,nanopowder
更新于2025-09-04 15:30:14