- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2018
- thin-film transistors
- N2O plasma treatment.
- amorphous InGaZnO
- gate-bias stress
- stability
- Electronic Science and Technology
- Peking University
-
Bifacial amorphous Si quintuple‐junction solar cells for IoT devices with high open‐circuit voltage of 3.5V under low illuminance
摘要： Hydrogenated amorphous Si(a‐Si:H) quintuple‐junction solar cells, which consist of a‐SiOx:H/a‐SiOx:H/a‐Si:H/a‐SiOx:H/a‐SiOx:H, were fabricated by plasma CVD method. The total thickness was 0.6‐0.8 μm. Irradiation intensity (Pin) dependence of the open circuit voltage (Voc) of quintuple‐junction solar cells was measured. The decreasing amount ΔVoc (1/10) of the open‐circuit voltage when the irradiation intensity became 1/10 was 62mV/cell. Voc drops rapidly from around the irradiation intensity of 1mW/cm2 (approximately 1,000 lux). This large Voc reduction is due to leakage current. Then, we discussed the origin of the leakage current, and, finally, by improving the leakage current, a very high open‐circuit voltage Voc of 3.5 V was demonstrated under LED light illumination. Furthermore, we theoretically analyzed Voc as a function of the irradiation intensity, including effects of the leakage current and the film quality of i‐a‐Si(O):H. It was found from the simulation results that it is necessary to increase the shunt resistance Rsh and to lower the defect density of i‐a‐Si(O):H in order to obtain a sufficient Voc‐Pin characteristics for IoT devices application under low illuminance.
关键词： solar cell,amorphous silicon,quintuple‐junction,low illuminance
更新于2025-09-11 14:15:04
-
Long-Term Behavior of Hydrogenated Amorphous Silicon Thin-Film Transistors Covered With Color Filters for Use in Optical Sensors
摘要： This work investigates the long-term behavior of photo thin-film transistors (TFTs) that are covered with color filters and based on hydrogenated amorphous silicon (a-Si:H) technology. Based on the electrical characteristics and the optical responses of these TFTs as measured under different stress conditions, a new method for driving a photo TFT with a negative gate-source voltage is proposed to suppress the degradation of the photocurrent. The effectiveness of the newly proposed method is verified using our previously developed white-light photocurrent gating (WPCG) structure, the measurement of photocurrents, and the established models of red, green, and blue photo TFTs. An accelerated lifetime test of the fabricated circuit was carried out at 70 ?C and under the illumination of ambient light for 504 hours, demonstrating that the proposed method improves the long-term reliability of optical sensors.
关键词： optical sensor,Hydrogenated amorphous silicon thin-film transistor,long-term reliability
更新于2025-09-11 14:15:04
-
Efficacy of erbium-doped yttrium aluminum garnet laser with casein phosphopeptide amorphous calcium phosphate with and without fluoride for remineralization of white spot lesions around orthodontic brackets
摘要： Objective: This study aimed to assess the efficacy of erbium?doped yttrium aluminum garnet (Er:YAG) laser, pastes containing casein phosphopeptide amorphous calcium phosphate (CPP?ACP) with and without fluoride and their combination for prevention of white spot lesions in the enamel. Materials and Methods: This in vitro experimental study was conducted on 90 extracted sound premolars. The teeth were then randomly divided into six groups of 15: (1) Control, (2) laser, (3) CPP?ACP with fluoride (GC MI Paste, Recaldent? 900 ppm as NaF), (4) CPP?ACP without fluoride (GC Tooth Mousse Recaldent?), (5) laser + CPP?ACP with fluoride, and (6) laser + CPP?ACP without fluoride. In each group, enamel surface was exposed to the remineralizing agent. The teeth were then subjected to pH cycling for 14 days. The teeth were then sectioned, polished, and underwent cross?sectional microhardness testing at 20–160 μ depth quantitatively. Using the Simpson’s rule, the amount of mineral loss was calculated in each group. Statistical Analysis Used: ANOVA was used for the comparisons, and Tukey’s test was applied for pairwise comparisons. Results: The highest mean volume percentage of microhardness at 20–60 μ depth belonged to the group laser + CPP?ACP with fluoride and the lowest belonged to the control group (P = 0.001). The differences were not significant at 80?120 μ depth (P > 0.05). These finding are confirmed according to ?Z (mineral loss). Conclusion: Based on these results, Er: YAG laser was able to decrease demineralization and was a potential alternative to preventive dentistry and was more effective when combined with CPP?ACP products.
关键词： Casein phosphopeptide amorphous calcium phosphate,white spot lesion,erbium-doped yttrium aluminum garnet laser
更新于2025-09-11 14:15:04
-
Phase Transition of SiO <sub/>2</sub> Nanoparticles Prepared from Natural Sand: The Calcination Temperature Effect
摘要： In this paper, we systematically report the synthesis of nano silica powder from natural silica sand by a continuous process. Extraction of sodium silicate from silica sand was through a hydrothermal process, then sodium silicate was ready to be used as a precursor in the form of silicate slurry by coprecipitation process. The silicate slurry of SiO2.XH2O was then dried in a furnace at 150 °C for 4 hours until obtaining a pure white SiO2 powder. At a calcination temperature of 900 °C, the sample was then tested by XRD to analyze the transformation of the crystal phase of SiO2 nanoparticles. Identification of functional group absorption was undertaken by FTIR test, and the particle grain microstructure was analyzed by SEM. At calcination temperature of 900 °C, the SiO2 silica nanoparticles experienced a change of phase from amorphous to crystal or amorphous-cristobalite phase; a shift in stiffness for positions of functional group absorption of Si-O stretching or LO functional groups, Si-O stretching or TO, Si-O-Si bending and Si-O-Si rocking and OH-functional groups occurred; the growth of particle grains happened with a spherical and oval trend, with a larger size. SiO2 nanoparticles were successfully synthesized by a continuous method and 900 °C calcination temperature had a significant effect on structural phase changes, the formation of siloxane functional groups, silanol, and grain growth on SiO2 nanoparticles.
关键词： calcination,nanoparticle,amorphous,cristobalite,natural sand,Silica
更新于2025-09-11 14:15:04
-
Hydrogenated amorphous carbon films with different nanostructure: a comparative study
摘要： The introduction of curved graphite fragments into hydrogenated amorphous carbon films has been studied, and their contents are always estimated by TEM and Raman. Here, we detailedly discussed the advantage and disadvantage of TEM and Raman fit method. Combined with FTIR results, we claified the chemical structures of the structural films and the bonded sites of doped H. The curved graphite structures included hexahydric carbon rings, and amorphous carbon (a-C) structures had rich olefinic groups and H. Finally, the differences among TEM, Raman, FTIR and H analysis in terms of the contents of curved graphite fragments were discussed.
关键词： FTIR,nanostructure,Raman,a-C:H,hydrogenated amorphous carbon film
更新于2025-09-10 09:29:36
-
[IEEE 48th European Solid-State Device Research Conference (ESSDERC 2018) - Dresden (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - Low Temperature and Radiation Stability of Flexible IGZO TFTs and their Suitability for Space Applications
摘要： In this paper, Low Earth Orbit radiation and temperature conditions are mimicked to investigate the suitability of flexible Indium-Gallium-Zinc-Oxide transistors for lightweight space-wearables. Such wearable devices could be incorporated into spacesuits as unobtrusive sensors such as radiation detectors or physiological monitors. Due to the harsh environment to which these space-wearables would be exposed, they have to be able to withstand high radiation doses and low temperatures. For this reason, the impacts of high energetic electron irradiation with fluences up to 1012 e-/cm2 and low operating temperatures down to 78 K, are investigated. This simulates 278 h in a Low Earth Orbit. The threshold voltage and mobility of transistors that were exposed to e- irradiation are found to shift by +0.09 ± 0.05V and -0.6 ± 0.5cm2 V-1 s-1. Subsequent low temperature exposure resulted in additional shifts of +0.38 V and -5.95 cm2 V-1 s-1 for the same parameters. These values are larger than the ones obtained from non-irradiated reference samples. If this is considered during the systems’ design, these devices can be used to unobtrusively integrate sensor systems into space-suits.
关键词： amorphous oxides,flexible electronics,thin film transistors,wearables,space applications
更新于2025-09-10 09:29:36
-
Use of Aggregation-Induced Emission for Selective Detection of Phase Transformation during Evaporative Crystallization of Hexaphenylsilole
摘要： Crystallization of organic molecules is quite complicated because the crystallization process is governed by the weak intermolecular interactions. By exploiting the aggregation-induced emission (AIE), we attempted to realize the selective detection of phase transformation during the evaporative crystallization of hexaphenylsilole (HPS), which shows different fluorescence colors in the amorphous and crystalline phases. No fluorescence emission was observed in the HPS solution immediately after dropping on the glass substrate due to the non-radiative deactivation induced by intramolecular rotational or vibrational motion, suggesting that HPS exists as a monomer in solution. As time elapsed after dropping, green emission first appeared, which changed to blue after solvent evaporation, because of phase transformation from the amorphous state to the crystalline state. This phenomenon supports not only the two-step nucleation model involving an intermediate such as a liquid-like cluster prior to nucleation, but also the real time-detection of Ostwald’s rule of stages during evaporative crystallization.
关键词： molecular interaction,amorphous-crystal phase transformation,AIE,Ostwald’s rule of stages,evaporative crystallization
更新于2025-09-10 09:29:36
-
Selective brookite polymorph formation related to the amorphous precursor state in TiO2 thin films
摘要： A wide variety of brookite TiO2 synthesis methods have been published over the past several decades, but few studies discuss the underlying mechanism that stabilizes brookite over its stable counterparts, rutile and anatase. Here, we investigate of the effect of pulsed laser deposition parameters on the as-deposited amorphous precursor titania thin films, which subsequently crystallize into stable and metastable TiO2 polymorphs upon annealing. We find that oxygen pressure in the deposition chamber strongly influences the non-equilibrium state of the amorphous precursor, which ultimately allows for selective polymorph formation. Rutile forms as the dominant phase at low pO2 < 0.1 mTorr, while anatase is favored at high pO2 > 5 mTorr. Brookite forms primarily at intermediate pO2 (0.5–1.0 mTorr). Controlling the amorphous structure (i.e. Ti—O bonding and polyhedral arrangement) of the precursors via oxygen deficiency is therefore likely for the selective formation of crystalline TiO2 polymorphs from sub-stoichiometric amorphous precursors. Directing phase selectivity by manipulating the structure and internal energy of the precursor amorphous state may have tremendous potential for synthesis of metastable crystalline phases that exhibit more desirable properties in comparison to their stable counterparts.
关键词： Amorphous precursors,Selective crystallization,Polymorphs,Oxygen deficiency,Thin films,TiO2
更新于2025-09-10 09:29:36
-
Amorphous InZnO:Li/ZnSnO:Li dual-active-layer thin film transistors
摘要： Amorphous Li-doped InZnO and ZnSnO (IZO:Li/ZTO:Li) dual-active-layer thin film transistors (TFTs) were fabricated by radio-frequency (RF) magnetron sputtering. The transmittance of the dual-stacked IZO:Li/ZTO:Li thin film was over 85% in the visible range. X-ray diffraction (XRD) result indicated that the thin film was amorphous. The influence of ZTO:Li layer thickness on the electrical characteristics and bias-stress stability of the dual-active-layer TFT was investigated. With the increasing thickness of ZTO:Li thin film, the saturation mobility (μSAT) increased firstly and then decreased, while the threshold voltage (VTH) shifted to the positive direction. The TFT with the optimized ZTO:Li thickness showed a superior performance with a μSAT of 33.2 cm2/V·s, a VTH of 3.2 V, a sub-threshold swing (SS) of 0.6 V/decade and a current on/off (ION/IOFF) up to 3.2 × 108.
关键词： B. Sputtering,A. Semiconductors,D. Electrical properties,A. Thin films,A. Amorphous materials
更新于2025-09-10 09:29:36
-
Three-Mode Modulation Electrochromic Device with High Energy Efficiency for Windows of Buildings Located in Continental Climatic Regions
摘要： A sustainable use of energy in buildings demands energy-efficient windows. A new design concept for electrochromic (EC) smart windows, easy to implement at the industrial level, is introduced here. It enables simultaneous control of visible and near-infrared (NIR) solar radiation, thus contributing to reduce heating and cooling loads especially in buildings located in areas experiencing wide daily temperature ranges. The EC device comprises amorphous indium zinc oxide, a conducting oxide transparent in the visible and NIR spectral regions, as nonactive layer, and a sol–gel protonic ionic liquid-doped di-ureasil electrolyte displaying high transparency and proton conductivity. The device offers three voltage-operated modes: bright hot (+3.0 V: transmittances of 70/83% at 555/1000 nm), semi-bright warm (?2.0 V: transmittances of 37/35% at 555/1000 nm), and dark cold (?2.5 V: transmittances of 6/4% at 555/1000 nm). Its main figures of merit are: high switching efficiency (transmittance variations of 64/79% at 555/1000 nm), high optical density modulation (1.1/1.3 at 555/1000 nm), high optical contrast ratio in the visible region (lightness variation of ≈43), good cycling stability, and unprecedented coloration efficiency (?12538/?14818 cm2 C?1 and +2901/+3428 cm2 C?1 at 555/1000 nm), outstanding optical memory (transmittance variation loss of only 24% more than 4 months after coloration), and self-healing ability following mechanical stress.
关键词： di-ureasil hybrid,N-butylimidazolium trifluoromethanesulfonate,visible- and NIR-controlled electrochromic devices,amorphous indium zinc oxide,energy-efficient smart windows for buildings
更新于2025-09-10 09:29:36