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Biocompatible and sustainable power supply for self-powered wearable and implantable electronics using III-nitride thin-film-based flexible piezoelectric generator
摘要： Energy harvesters that scavenge biomechanical energy are promising power supply candidates for wearable and implantable electronics. Of the most widely used energy harvesters, piezoelectric generators can generate more electric charge than their triboelectric counterparts with similar device size, thus are more suitable to make compact wearable devices. However, most high-power piezoelectric generators are made from lead zirconate titanate, making them undesirable for wearable applications due to the toxic lead element. In this study, a flexible piezoelectric generator (F-PEG) is fabricated with chemically stable and biocompatible Group-III-nitride (III-N) thin film by a layer-transfer method. The III-N thin-film F-PEG can generate an open-circuit voltage of 50 V, a short-circuit current of 15 μA, and a maximum power of 167 μW at a load resistance of 5 M?. Applications of the III-N thin-film F-PEG are demonstrated by directly powering electronics such as light-emitting diodes and electric watches, and by charging commercial capacitors and batteries to operate an optical pulse sensor. Furthermore, the III-N thin-film F-PEG shows good durability and a stable output after being subjected to severe buckling tests of over 30,000 cycles.
关键词： flexible,piezoelectric generators,thin film,III-nitride,self-powered system,biocompatible
更新于2025-09-23 15:23:52
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Thermal evolution of morphological, structural, optical and photocatalytic properties of CuO thin films
摘要： Nanostructured CuO thin films were synthesized by thermal evaporation and annealing. Structural, optical and morphological changes in the CuO film upon annealing and their overall impact on its photocatalytic activity were investigated employing X-ray diffraction, UV–Vis absorption spectroscopy, atomic force microscopy and field emission scanning electron microscopy. Significant modifications in the morphological, optical, structural and photocatalytic behavior of nanostructured CuO thin film were observed upon thermal annealing. Thermal annealing led to the growth of CuO nanoparticles and the average size of CuO nanoparticles increased from 23 nm to 293 nm as the annealing temperature was increased to 600oC. CuO thin film sample annealed at 400 ? C exhibited superior photocatalytic activities over other samples for the degradation of malachite green and methylene blue dyes in 120 and 160 min, respectively. The improved photocatalytic behavior of CuO thin film annealed at 400 ? C is attributed to its narrower band gap, improved utilization of sunlight and enhanced adsorption of dye due to increased surface area arising from formation of CuO nanoparticles and their aggregates at the surface.
关键词： Methylene blue,CuO,Thin film,Photocatalysis,Malachite green
更新于2025-09-23 15:23:52
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A New Catalyst Ti Doped CdO Thin Film for Non-Enzymatic Hydrogen Peroxide Sensor Application
摘要： A new material, Ti doped CdO (Ti: CdO) semiconductor, is firstly reported by this work for electrochemical non-enzymatic hydrogen peroxide (H2O2) sensor applications which was deposited by a simple, versatile and cost-effective chemical spray pyrolysis method on indium doped tin oxide (ITO) substrate. In the basic studies, first, the withstanding of cubic crystal phase along with worthy crystalline nature is discerned on CdO film after Ti doping, here only the preferentially orientated (200) diffraction plane shifted to (111). Subsequently, the irregular spherically shaped CdO nanoparticles (NPs) morphology changed as nearly uniform size with Ti doping is noticed with respect to thermal pyrolytic decomposition process. The existence of Ti atoms in Ti: CdO film is authentically identified and confirmed using EDX and XPS studies respectively. The absorption and emission properties of CdO and Ti: CdO films are studied and confirmed their narrow band gap nature. Importantly, the Ti: CdO film shows pronounced electrocatalytic activity for the reduction of hydrogen peroxide (H2O2) as compared to pure CdO. Hence, the non-enzymatic electrochemical sensing of Ti: CdO electrode shows a lower detection limit 0.4 μM with the linear range of 10-190 μM which displayed a fast amperometric response for 5 s with sensitivity of 0.27 μA μM-1 cm-2 toward H2O2 detection. This result will boost exploring a new opportunity for the deposition of other metal oxides and semiconductors by using a simple chemical spray pyrolysis method for detection of non-enzymatic H2O2 sensor applications.
关键词： H2O2 sensor,and selectivity,Chemical spray pyrolysis,Ti: CdO thin film
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Conference on Electron Devices and Solid State Circuits (EDSSC) - Shenzhen (2018.6.6-2018.6.8)] 2018 IEEE International Conference on Electron Devices and Solid State Circuits (EDSSC) - Analysis of 1/f Noise for Organic TFTs Considering Mobility Power-Law Parameter
摘要： Based on carrier number fluctuation model, 1/f noise is analyzed for organic thin-film transistors (TFTs) at low drain voltage. The carrier mobility is gate-voltage-dependent, and is described by a power-law function. The mobility power-law parameter α determines the relationship between drain current noise power spectral density (PSD) SIDS and drain current IDS, and it is found that SIDS /I 2 DS when α = 1. It is different from the well-known rule for the MOSFETs with the constant carrier mobility: When SIDS /I 2 DS , Hooge’s mobility fluctuation model dominates the 1/f noise.
关键词： carrier mobility,Thin-film transistor (TFT),analytical model,low frequency noise
更新于2025-09-23 15:23:52
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Critical impact of gate dielectric interfaces on the trap states and cumulative charge of high-performance organic thin field transistors
摘要： In the operation of OFETs, the electrical properties are strongly dependent on the merits of the constituting layers and the formed interfaces. Here we study the trap states variations at the interface between the organic semiconductor pentacene and polymer insulators. With ZrO2 dielectric modified by polymers and find a 10 × decrease in the density of trap states at the semiconductor/insulator interface, bring about the charge carrier mobility increase from 0.058 cm2/Vs to 0.335 cm2/Vs. In addition, when compare to the thicker films at the same applied gate voltage, the thinner film would lead to enhanced coupling capability and more charges cumulative cumulated at the channel region, which is pivotal for optimizing the performance of OFETs. The results prove that the property of the insulator layer could impact largely on the device performance.
关键词： Organic thin film transistor,Cumulative charge,Insulator/semiconductor interface,Trap states
更新于2025-09-23 15:23:52
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Effect of structures and substrate temperatures on BaZn0.06Bi0.94O3- perovskite-based NTC thermistor thin films
摘要： Negative temperature coefficient (NTC) thermistor thin films based on perovskite-type BaBiO3 (BB) and BaZn0.06Bi0.94O3-δ (BZB) were successfully prepared by radio frequency (RF) magnetron sputtering method on Pt substrate. The crystal structure and grain morphology of the BZB and BB films deposited at different substrate temperatures (25–200 °C and 200 °C, respectively) were examined by X-ray diffraction (XRD) and atomic force microscope (AFM). The substrate temperature had a significant influence on the crystallinity and phase structure, in which the main crystalline phases with the cubic and tetragonal BaBiO3-based perovskite structures could be obtained on the substrate temperatures of 100 °C and 200 °C, respectively. On the other hand, the electrical properties were analyzed by measuring the resistance temperature (ρ-T) characteristics, and all the thin films exhibited good NTC thermistor characteristics. In addition, the grain (Rg) and grain boundary (Rgb) contribution to the total resistance were estimated by three parallel R-CPE equivalent circuits in series, in which the main contribution of resistance for BZB thin film deposited at 200 °C was derived from Rg response rather than that in Rgb at the higher temperature range. This was one of the most important reasons why this sample had a good NTC behavior, and this result was confirmed by the current-voltage (I-V) characteristics analysis. For the BB film, the room-temperature resistivity (ρ25) was 1540 Ω cm (B25/85 –3240 K), while the ρ25 value decreased to approximately 1156 Ω cm (B25/85 –3183 K) for BZB film deposited at a same substrate temperature (200 °C). This is mainly due to the change in crystal structural characteristics. It is believed that the substitution of Zn2+ for BB thin films deposited at an appropriate temperature will be useful for low-resistance applications as novel thin film NTC thermistors.
关键词： Substrate temperature,NTC thermistor,Electrical properties,BaBiO3,Thin film
更新于2025-09-23 15:23:52
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Structural and temperature-dependent optical properties of thermally evaporated CdS thin films
摘要： In this work, structural and temperature dependent optical properties of thermally evaporated CdS thin films were investigated. X-ray diffraction, energy dispersive spectroscopy and Raman spectroscopy experiments were carried out to characterize the thin films and obtain information about the crystal structure, atomic composition, surface morphology and vibrational modes. Temperature-dependent transmission measurements were performed in between 10 and 300 K and in the spectral range of 400–1050 nm. The analyses of transmittance spectra were accomplished by two different methods called as the absorption coefficient and the derivative spectrophotometry analyses. All evaluated band gap energy values at each studied temperature were in good agreement with each other depending on the applied analyses techniques. Room temperature gap energy values were found around 2.39 eV and 2.40 eV from absorption coefficient and derivative spectrophotometry analyses, respectively. Band gap energy depending on the sample temperature was studied under the light of two different models to investigate average phonon energy, electron phonon coupling parameter and the rate of change of band gap energy with temperature.
关键词： Thin film,CdS,Optical properties
更新于2025-09-23 15:23:52
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CO Gas Sensor based on E-beam Evaporated ZnO, MgZnO and CdZnO Thin Films: A Comparative Study
摘要： This paper reports a comparative study of electron-beam evaporated ZnO, MgZnO and CdZnO thin film based gas sensor. At room temperature (RT), these semiconductive thin films were deposited on Si/SiO2 substrate and an interdigitated pattern of chromium electrode deposited on these films. Device properties such as structural, optical and electrical have been reported and analyzed. The sensors have been tested at different operating temperatures. At 250 ℃, the sensor shows the best response for CdZnO thin films. We have obtained sensor response 4.86 with response time 15 sec for 100 PPM carbon mono oxide (CO) gas concentration for CdZnO thin film. Based on experimental results, Cd-doped ZnO has been found most suitable among these semiconducting metal oxides, when used as a CO gas sensor. A correlation between structural, optical and electrical properties with these thin films has also been established.
关键词： Thin film,ZnO,MgZnO,CO Gas sensor,CdZnO,E-beam evaporation
更新于2025-09-23 15:23:52
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Highly conductive, transparent and metal-free electrodes with a PEDOT:PSS/SWNT bilayer for high-performance organic thin film transistors
摘要： Conductive organic materials including polymers, small molecules, and carbon nanotubes (CNTs) are a promising alternative to inorganic materials in electronic devices. Conventionally, organic electrodes employing CNTs are designed using functionalization of their surfaces or formation of nanocomposites with a conductive polymer. However, phase separation limits the concentration of CNTs in a polymer matrix, hindering the formation of highly dense CNT networks and leading to poor electrical conductivity. In this paper, we introduce bilayer electrodes comprising poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and single-walled CNTs (SWNTs) chemically modified by HNO3 treatment. Impressive conductivities of 2432 and 2438 S cm?1 are found for the SWNT/PEDOT:PSS (S/P) and PEDOT:PSS/SWNT (P/S) electrodes, respectively. Further, an increase in the work function of the electrodes after HNO3 treatment lowers the hole injection barrier, which facilitates hole injection from pentacene. The smooth surface of PEDOT:PSS also contributes to growth of large pentacene grains; consequently, the field-effect mobility of pentacene-based thin film transistors is 1.88 cm2 V?1 s?1 when the P/S electrode is employed. The metal-free electrodes also exhibit a high optical transparency of 88.7%, which suggests that they have great potential for applications in optoelectronics.
关键词： Electrode,PEDOT:PSS,Carbon nanotube,Pentacene,Thin film transistor
更新于2025-09-23 15:23:52
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RF Characterization of NiO and TiO <sub/>2</sub> Based Metal-Insulator-Metal (MIM) Diodes on Flexible Substrates
摘要： This paper presents the fabrication and characterization of metal-insulator-metal (MIM) diodes on flexible substrates for RF and microwave circuit applications. Diodes using two types of insulators, titanium dioxide (TiO2) and nickel oxide (NiO), are investigated. These insulators are obtained using different oxidation techniques, i.e., in-situ oxidation for TiO2 and plasma oxidation for NiO. Asymmetric metal contacts (Ti-TiO2-Pd and Ni-NiO-Mo) are utilized to achieve nonlinear I–V characteristics. The fabricated diodes show strong non-linearity, high current densities, and low turn-ON voltage. The diodes show RF to dc rectification with near-ideal behavior and rectification sensitivity of 22 V/W (18 GHz) and 46 V/W (18 GHz) for TiO2 and NiO, respectively. NiO-based diodes barrier shows higher current density and higher cutoff frequency in comparison with TiO2 as expected diodes due to thinner oxide and lower dielectric constant. The diodes also work well as frequency doublers over a wide frequency range of 1–4 GHz for TiO2 and 2–10 GHz for NiO-based diodes. Good dc and RF performance of diodes indicate that good quality oxide can be achieved on plastic substrates and MIM devices can provide a perfect solution for RF and microwave circuits on a flexible substrate.
关键词： MIM diodes,rectification,Flexible electronics,harmonic generation,thin film devices,microwave circuits
更新于2025-09-23 15:23:52