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Determination of the Thin-Film Structure of Zwitterion-Doped Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate): A Neutron Reflectivity Study
摘要： Doping poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is known to improve its conductivity, however little is known about the thin film structure of PEDOT:PSS when doped with an asymmetrically charged dopant. In this study, PEDOT:PSS was doped with different concentrations of the zwitterion 3-(N,N Dimethylmyristylammonio)propanesulfonate (DYMAP), and its effect on the bulk structure of the films characterized by neutron reflectivity. The results show that at low doping concentration, the film separates into a quasi bi-layer structure with lower roughness (10%), increased thickness (18%), and lower electrical conductivity compared to the un-doped sample. However when the doping concentration increases the film forms into a homogeneous layer and experiences an enhanced conductivity by more than an order of magnitude, a 20% smoother surface, and a 60% thickness increase relative to the pristine sample. Atomic force microscopy and profilometry measurements confirmed these findings, and AFM height and phase images showed the gradually increasing presence of DYMAP on the film surface as a function of the concentration. Neutron reflectivity also showed that the quasi bi-layer structure of the lowest concentration doped PEDOT:PSS is separated by a graded rather than a well defined interface. Our findings provide an understanding of the layer structure modification for doped PEDOT:PSS films that should be prove important for device applications.
关键词： neutron reflectivity,hole transporting layer,conductivity,film structure,zwitterion,PEDOT:PSS
更新于2025-11-14 15:19:41
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Effect of post-annealing on microstructure and piezoelectric properties of ZnO thin film for triangular shaped vibration energy harvester
摘要： In this paper, a triangular shaped piezoelectric vibration energy harvester (TS-PVEH) with zinc oxide (ZnO) thin films as the piezoelectric layer is reported. The effect of post-annealing temperature on the microstructure and piezoelectric performance of ZnO thin film deposited by magnetron sputtering method is investigated firstly. The results show that the optimum post-annealing temperature of 150 °C was the most beneficial to improve the piezoelectric properties of ZnO thin films. Four prototypes of TS-PVEH with different structure parameters are fabricated and optimized. The simulation and experiment results indicate that the height and width of the triangular structure have a significant influence on the vibration mode and the output performance of TS-PVEHs. The optimization results indicate that the third prototype has the best output performance. Its open-circuit voltage and short-circuit current are 290mV and 1.25 μA, respectively, when the vibration acceleration is 5m/s2 and the frequency is 56Hz. Moreover, it has the highest load power density of 0.035μW/cm2 when the load is 0.1MΩ.
关键词： Triangular substrate,ZnO thin film,Structure optimization,Post-annealing temperature,Vibration energy harvester
更新于2025-09-23 15:23:52
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Role of reactive gas on the structure and properties of titanium nitride films grown by plasma enhanced atomic layer deposition
摘要： The authors report on the role of various reactive gases on the structure and properties of TiN thin films prepared by plasma enhanced atomic layer deposition (PEALD) from tetrakis(dimethylamido) titanium. The reactive gas plays an important role determining the film structure and properties. Nitrogen-based plasma (N2 and NH3) resulted in low oxygen (~3%) and carbon (~2%) contamination and well-defined columnar grain structure. A nitrogen excess (~4%) was found in the films deposited using N2 plasma. The stoichiometric films and lowest resistivity (~80 μΩ cm) were achieved using NH3 plasma. Deposition using H2 plasma resulted in higher carbon and oxygen contamination (~6% for each element). The reactive gas also plays an important role in determining the grain size and preferential orientation. By varying the plasma chemistry, either (111) or (100) oriented films can be obtained. A mechanism determining the PEALD TiN preferential orientation is proposed. Finally, plasma induced degradation of the underlying dielectric layer is evaluated.
关键词： plasma enhanced atomic layer deposition,film structure,properties,titanium nitride,reactive gases
更新于2025-09-23 15:21:01
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High-performance plasmonic refractive index sensors via synergy between annealed nanoparticles and thin films
摘要： Plasmonic nanostructure-based refractive index (RI) sensors are the core component of biosensor systems and play an increasingly important role in the diagnosis of human disease. However, the costs of traditional plasmonic RI sensors are not acceptable to everyone due to their expensive fabrication process. Here, a novel low-cost and high-performance visible-light RI sensor with a particle-on-film configuration was experimentally demonstrated. The sensor was fabricated by transferring annealed Au nanoparticles (NPs) onto a thin gold film with polymethyl methacrylate (PMMA) as a support. RI sensitivities of approximately 209 nm/RIU and 369 nm/RIU were achieved by reflection and transmission spectrum measurements, respectively. The high sensitivity is due to the strong plasmon-mediated energy confinement within the interface between the particles and the film. The possibility of wafer-scale production and high working stability achieved by the transfer process, together with the high sensitivity to the environmental RI, provides an extensive impact on the realization of universal biosensors for biological applications.
关键词： high stability,transfer process,low cost,refractive index sensors,particle-on-film structure
更新于2025-09-23 15:19:57
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Micro-nano scale imaging and the effect of annealing on the perpendicular structure of electrical-induced VO2 phase transition
摘要： It was research hotspot that how to lower the threshold switching voltage (Vth), especially for the perpendicular structure of electrical-induced VO2 insulator-metal phase transition (MIT). This structure can reduce the Vth to the orders of 10-1 V. In micro-nano scale, combined with results of resistance change versus temperature, X-ray photoelectron spectroscopy measurements and conductive atomic force microscope, we had confirmed that V3+ was an important factor for electrical-induced VO2 thin MIT. On the one hand, joule heating produced by conductive V3+ region induced the surrounding VO2 region phase transition. On the other hand, with the annealing time increased from 0 min to 2 min at 470℃ in H2/N2 mixture gases, V3+ contents increased, thin film surface conductive areas increased, thin film resistance decreased, and finally resulted in threshold switching voltage decreased. Our experimental results were consistent with theory analysis. However, when the annealing time was too long (≥3 min), VO2 thin film threshold switching behavior disappeared, and current was linearly increased with voltage.
关键词： Perpendicular structure of electrical-induced VO2 MIT,Annealing process,Micro-nano scale current mapping,perpendicular VO2 thin film structure,threshold switching voltage
更新于2025-09-09 09:28:46