- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Microstrip broadband thin-film attenuators without via-hole-ground at millimeter wave frequencies
摘要： A comprehensive design methodology for microstrip broadband attenuators is presented. Closed-form design equations are given for two types of distributed attenuators. The attenuators are based on a cascade connection of thin-film resistors and microstrip line sections. The structure provides maximally flat attenuation and wideband performance without the need of plated via holes to ground, facilitating manufacture as well as achieving proper performance at millimeter wave frequencies. Experimental results demonstrate the validity of the technique applied to 3 dB and 13 dB broadband attenuators on alumina substrate up to 67 GHz. The proposed topology can be applied not only to MIC, but also to MMIC designs at the highest frequencies.
关键词： MM-wave,Thin-film microwave attenuator,Microstrip circuit
更新于2025-09-19 17:15:36
-
High performance n-type vertical organic phototransistors
摘要： In this manuscript, a solution-processed n-type organic phototransistor based on vertical structure thin-film transistors was proposed. Due to the vertical structure and short channel length (≈130 nm), the transistors exhibited excellent current density (15.4 mA/cm2) with high Ion/Ioff ratio (up to 105). On account of this structure, the face-on π-π stacking of P(NDI2OD-T2) was aligned with the charge transport direction, which facilitated charge transfer from source to drain electrode. Moreover, n-type organic phototransistors based on vertical thin-film transistors were demonstrated for the first time, in which the active layer was protected by the source-drain electrodes, resulting in the improvement of the stability of the device. Due to the nanoscale channel, efficient separation of electron-hole pairs and quick charge transfer can be achieved. Hence, high-performance n-type phototransistor was obtained with responsivity of 34.8 A/W, photosensitivity of 4.78×104, detectivity of 3.95×1013 Jones and external quantum efficiency up to 1.1×104 % under 400 nm illumination with a light intensity of 200 μW cm-2, which was much better than those reported n-type organic phototransistors. This work provided a strategy for the fabrication of high performance n-type organic phototransistor, which paved the way for its future application in the next-generation organic optoelectronics.
关键词： n-type organic semiconductor,Organic phototransistors,Vertical structure,Organic thin-film transistors
更新于2025-09-19 17:15:36
-
Enhanced Conversion Process in a Sub-wavelength Thin Upconversion Layer by Using Metamaterial Mirror
摘要： Because of finite bandgap, useful spectral ranges of semiconductors are limited for photovoltaic applications. The upconversion (UC) process is one of alternatives to extend the useful spectral range by converting long wavelength photons to short wavelength photons. For example, NaYF4 codoped Yb3+/Er3+ converts photons from near-infrared (970 nm) to visible (660 nm). However, in the form of a thin layer on a flat metal mirror, which is a representative structure to add UC layer into photovoltaic devices, the UC material exhibits low efficiency in optical devices because of its low absorption and conversion efficiencies. In this paper, the UC process is highly enhanced by a metamaterial mirror consisting of grooved silver surfaces. The absorption of UC material is improved by a factor of 5.3 due to increased light-matter interaction because the electric field is highly concentrated in the UC layer near the metal surface. The surface plasmon polariton (SPP) modes induced by a dipole emitter to a metal grooved surface enhance the spontaneous emission (SE) rate of the emission wavelength of UC material by a factor of 65 compared with a thin UC layer on flat mirror. Consequently, total efficiency of the UC process is 400 times more enhanced than the reference structure by magnetic mirror property and SPP modes of metamaterial mirror.
关键词： Metamaterial,Upconversion,Thin film
更新于2025-09-19 17:15:36
-
Hybrid gate dielectrics: a comparative study between polyvinyl alcohol/ $$\hbox {SiO}_{2}$$ SiO 2 nanocomposite and pure polyvinyl alcohol thin-film transistors
摘要： Polyvinyl alcohol (PVA) thin films as polymer gate dielectrics, with and without SiO2 nanoparticles were fabricated using spin-coating. Surface roughness and hydrophilicity of PVA and PVA/SiO2 thin films were studied by contact-angle measurements and atomic force microscopy. The dielectric properties were characterized via capacitance and leakage-current measurements on metal–insulator–metal structures. In order to further investigate the application potential of such materials as a replacement for conventional inorganic dielectrics such as SiO2 in organic thin-film transistors, devices were fabricated based on these polymers using α, ω-dihexylquaterthiophene as an active layer. Performance of the devices was realized by electrical measurements and Kelvin probe force microscopy. All transistors showed hole and electron mobilities in the low-voltage range. PVA/SiO2 films showed larger capacitance, less hydrophilicity, rougher surfaces and considerable leakage currents compared with those with neat PVA. Although integrating nanoparticles modified surface electronic properties and showed a shift in surface potential as observed in Kelvin probe force measurements, it appears that non-polymeric and neat polymeric dielectric materials could still be a privilege to nanocomposite polymeric dielectrics for optoelectronic applications.
关键词： ambipolar thin-film transistor,scanning probe microscopy (SPM),surface chemistry,electrical and structural properties,Polymer dielectrics
更新于2025-09-19 17:15:36
-
Studying the influence of deposition temperature and nitrogen contents on the structural, optical, and electrical properties of N-doped SnO2 films prepared by direct current magnetron sputtering
摘要： This report focuses on studying and investigating in detail the structural, electrical, and optical properties of p-type N-doped SnO2 (NTO) versus the deposition temperature and nitrogen content. P-type transparent conductive NTO films were deposited on quartz glass substrates using a direct current (DC) magnetron sputtering method. The substitution of oxygen by nitrogen in the SnO2 host lattice was verified using measurements such as X-ray photoelectron spectroscopy. The position of the N3? defect state in the band gap was determined using photoluminescence and ultra-violet-visible spectroscopy measurements. The data for the (110) to (101) rutile lattice planes changed, and the rutile (plane (101)) to cubic (plane (111)) SnO2 phase transition indicated the substitution of oxygen by nitrogen in the SnO2 host lattice. The best p-type conductive properties achieved were 8 × 10?2 Ω cm, 1.36 × 1019 cm?3, and 6.75 cm2 V?1 s?1 for the resistivity, hole concentration, and hole mobility, respectively, for film deposited at the optimum substrate temperature of 300 °C in a gas mixture of Ar and 50% N2.
关键词： deposition temperature,nitrogen content,p-type N-doped SnO2 thin film,X-ray photoelectron spectroscopy,DC magnetron sputtering,X-ray diffraction
更新于2025-09-19 17:15:36
-
[IEEE 2018 IEEE 13th Nanotechnology Materials and Devices Conference (NMDC) - Portland, OR, USA (2018.10.14-2018.10.17)] 2018 IEEE 13th Nanotechnology Materials and Devices Conference (NMDC) - Magnetic Characterization of Cobalt Selenide and Nickel Selenide Thin Films
摘要： Transition metal dichalcogenides (TMDCs) are a family of materials whose crystalline structure consists of a layer of transition metal atoms sandwiched between 2 layers of chalcogenide atoms. Some of these materials can be grown in 2D hexagonal phase and show tunability of their electrical and magnetic properties based on layer thickness. One aspect of these materials that has received little attention is their magnetic properties. Hence, we have investigated magnetic properties of CoSe and NiSe their heterostructure. The reason for choosing these intrinsically ferromagnetic transition metal atoms based TMCs was to examine how reduction from the bulk to 2D films would influence the magnetic activity of these samples. In order to produce large area films, we have employed atomic layer deposition (ALD) for growth of uniform, few layer-thick films. First the composition and crystal structure of these films are characterized, and then their magnetic properties analyzed. We have found that thin films of both these materials show mostly paramagnetic behavior.
关键词： cobalt selenide,magnetic properties,Transition metal chalcogenides,thin film,nickel selenide
更新于2025-09-19 17:15:36
-
Effects of different annealing processes on optoelectronic and bending fatigue properties of AgZr and ITO/AgZr thin film metallic glass
摘要： Transparent conducting oxide (TCO) films are widely used throughout the optoelectronics industry. The present study explores the optoelectronic responses of AgZr (AZ) and ITO/AgZr (IAZ) thin film metallic glasses (TFMGs) with different Ag and Zr compositions and processed by two different annealing methods, namely furnace annealing (FA) and laser annealing (LA). Among the various as-deposited AZ and IAZ films, the ITO/Ag66Zr34 (IA6Z) film has the highest optical transmittance (55.7%) and the lowest sheet resistance (145.8 Ω/□). For the FA samples, an annealing temperature of 300 °C results in the optimal optoelectronic properties, namely a transmittance of 68.4% and a sheet resistance of 47.2 Ω/□. For the LA samples, the optimal processing conditions (a pulse energy of 2.5 μJ and a repetition rate of 150 kHz) yield optical transmittance and sheet resistance values of 64.0% and 17.8 Ω/□ respectively. The optimal LA processing conditions increase the Haacke figure of merit of the IA6Z sample from 2.0 × 10?5 under the as-deposited condition to 6.5 × 10?4 Ω?1 under the annealed condition; corresponding to a 32.5-fold improvement. Finally, the relative change in resistivity (ΔR/R0, where R0 is the initial resistivity, Ri is the measured resistivity after a certain number of cycles, and ΔR is Ri - R0) of the as-deposited IA6Z sample following fatigue testing (10,000 cycles) with a bend radius of 7 mm (ΔR/R0 = 0.49) is significantly lower than that of a pure ITO film of roughly equivalent thickness (ΔR/R0 = 0.93).
关键词： Laser annealing,Bi-layered electrode,Furnace annealing,Thin film metallic glass
更新于2025-09-19 17:15:36
-
[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - Suppression of Propagation Losses in TC SAW Resonators Using Thin Plates of LiTaO3 Bonded to Quartz Substrates
摘要： Suppression of Propagation Losses in Thin-Film Lithium Niobate Optical Waveguides
关键词： Lithium Niobate,Thin-Film,Optical Waveguides,Quasi-Phase Matching,Propagation Losses
更新于2025-09-19 17:15:36
-
Pressureless sintering of ZnO thin film on plastic substrate via vapor annealing process at near-room temperature
摘要： In this work, Vapor Annealing Sintering (VAS) process was introduced for low-cost pressureless producing dense Zinc Oxide (ZnO) thin films deposited from nanoparticles at near-room temperature (50 °C). Spontaneous densification evolution from nanoparticulate to a dense film via a dissolution-diffusion-reprecipitation mechanism was observed exposing ZnO layers to the vapor of an acetic acid aqueous solution at isothermal condition. The influence of the annealing on the optical properties of the treated films was investigated in order to study the structural changes. The proposed method can allow new opportunities for simple and low-cost ceramics thin film manufacturing also involving pressure and temperature-sensitive materials.
关键词： Zinc oxide,Thin film,Nanoparticles,Sintering,Vapor annealing
更新于2025-09-19 17:15:36
-
NO<sub>2</sub> gas sensing performance enhancement based on reduced graphene oxide decorated V<sub>2</sub>O<sub>5</sub> thin film
摘要： Here, we demonstrate the improved NO2 gas sensing properties based on reduced graphene oxide (rGO) decorated V2O5 thin film. Excluding the DC sputtered grown V2O5 thin film, rGO was spread over V2O5 thin film by drop cast method. The formation of several p-n heterojunctions is greatly affected by the current-voltage relation of rGO decorated V2O5 thin film due to p-type and n-type nature of rGO and V2O5, respectively. Initially with rGO decoration on V2O5 thin film, current decreases in comparison to V2O5 thin film, whereas depositing rGO film on glass substrate, current increases drastically. Among all sensors, only rGO decorated V2O5 sensor revealed maximum NO2 gas sensing response for 100 ppm at 150°C, and helped achieve approximately 61% times more response than the V2O5 sensor. An elaborated mechanism for an extremely high sensing response is attributed to the formation and modulation of p-n heterojunction at the interface of rGO and V2O5. In addition, the presence of active sites like oxygenous functional groups on rGO surface also enhances the sensing response. On that account, the sensor based on rGO decorated V2O5 thin film is highly suitable for the purpose of NO2 gas sensing. This enables timely detection of the gas, further prevent the ecosystem from its harmful effects.
关键词： NO2 gas,relative response,DC sputtering,p-n heterojunction,rGO decorated V2O5 thin film
更新于2025-09-19 17:15:36