Highest FOM Research Articles

ZnO/metal/ZnO (metal = Ag, Pt, Au) films for energy-saving in windows application

In this paper, the impact of different metals (Ag, Pt and Au) on the ZnO/metal/ZnO samples, being coated on a Glass substrate via RF/DC magnetron sputtering system, is investigated. The structural, optical, and thermal properties of the as-prepared samples were systematically studied for the purpose of storage and production of energy in industry. Our results show that these layers can be used as suitable coatings on building windows for energy storage applications. In the same experimental conditions, the case of Au as the intermediate layer has shown to have better optical and electrical conditions. Then the Pt layer also led to further improvement of the properties of the samples rather than those of the Ag. Moreover, the ZnO/Au/ZnO sample has shown the highest transmittance at the visible region (68.95%) and the highest FOM (5.1 × 10–4 Ω−1). Therefore, it can be considered as relatively the optimum sample in order for the building windows to save energy because of its low U-value (2.16 W/cm2 K) and low emissivity (0.45). Finally, by applying the equivalent voltage of 12 V at the ends of the sample, the surface temperature of sample has risen from 24 to 120 °C.

Effect of heat treatment on optical, electrical and thermal properties of ZnO/Cu/ZnO thin films for energy-saving application

In this work, the effect of annealing on the ZnO/Cu/ZnO films prepared by an RF/DC magnetron sputtering system was studied. Structural, optical, and thermal properties of both the as-prepared samples and their annealing data were systematically investigated. Our evaluation shows that these layers can be used as suitable coatings in energy storage applications. The ZnO/Cu/ZnO sample after annealing at 400 °C has the lowest resistivity (14.04Ω/sq), highest FOM (6.37 × 10−4 Ω−1), and lowest emissivity (0.16). It can also be chosen as the best coating on building windows to save energy because of its high transmittance at 550 nm (68%) and low U-value (1.63 W/Cm2.K).

Optimization of plasmonic sensors based on sinusoidal and rectangular gratings

Surface plasmon resonance (SPR) sensors based on metal gratings have received much attention for designing compact and portable biosensors. In this paper, we systematically optimize SPR sensors based on sinusoidal and rectangular gratings to improve the performance of this kind of sensors. A parameter (FOM*) is defined to evaluate the sensor performance, which combines the sensitivity, FWHM, and depth of the SPR absorption peak. We find that grating period of 560 nm is suitable to locate the SPR peaks in the optimal response range of silicon detectors and ensures high sensitivity. For sinusoidal gratings, the highest FOM* of 99.25 is achieved at grating depth of 15 nm. The highest FOM* for rectangular grating with continuous metal film is 123.70 when grating depth and duty cycle are 12 nm and 0.3, respectively. With grating depth of 24 nm and duty cycle of 0.8, the highest FOM* of 25.23 is obtained for rectangular grating with discontinuous metal film. These optimization results can be directly used to improve the detection limit of compact SPR sensors.

Printable High‐Aspect Ratio and High‐Resolution Cu Grid Flexible Transparent Conductive Film with Figure of Merit over 80 000

AbstractFigure of merit (FOM), the ratio of electrical conductance to optical transparency, is an important metric to evaluate transparent conductive film (TCF). The conductivity of commonly used flexible TCF such as indium tin oxide is generally limited and their FOM is lower than 300. In this study, a high‐performance copper (Cu) metal‐mesh TCF with the highest FOM ever reported, up to 8 × 104, is fabricated through an additive manufacturing process of blading a silver seed layer and selective electroplating of Cu. With this strategy, Cu metallic lines completely constrained in roll‐to‐roll imprinted microgrooves achieve high aspect ratio of 2 with 4 µm width and 8 µm depth, which has very clean and smooth edges. This embedded Cu metal mesh exhibits an ultralow sheet resistance down to 0.03 Ω □−1 at 86% optical transmittance. It is demonstrated that the Cu metal mesh has remarkable mechanical flexibility, high environmental stability at high temperature and humidity, and durability over repeated heating cycles. The Cu metal mesh is employed as a flexible transparent heater to attach to the windshield of a car, showing rapid heating at low voltage and effective removal of snow.

Coupled plasmon in the rounded Ag hexagonal nanoplate dimer

The subtle changes in the edges and corners of nanoparticles are the common occurrence during the manufacturing process of them which it affects on the nanoparticles sensing properties. In this work, we studied rounding effect on sensing properties of silver hexagonal nanoplate dimer by using the discrete dipole approximation (DDA). In these nanoplates three main plasmonic bands arise (dipole, octupole and anti-bonding modes). Both dipole and octupole modes are strongly affected by changes in the refractive index of medium and blue shift under the influence of the edges rounding. Our results show that hexagonal dimers with the least gap distance (g = 1 nm) have the largest extinction cross section and the maximum hybridization of plasmon peak.Furthermore, our results show that octupole mode has the highest FOM in both types of perfect and rounded hexagonal nanoplate's dimer, and the FOM of rounded hexagonal dimer is less than the perfect hexagonal nanoplate dimers. This study may be used to build more advanced sensing devices based on metallic nanoparticles.

Figure of merit of X‐type hexaferrite (Ba2Co2Fe28O46) for mobile antenna applications

AbstractWe report a Ba2Co2Fe28O46 (Co2X) hexaferrite, which has a high figure of merit (FOM = μ′/tan δμ) over the frequency range from 800 MHz to 1 GHz. The Co2X hexaferrite was prepared by the conventional solid‐state reaction. The calcined and sintered Co2X hexaferrites were characterized with a vibrating sample magnetometer and an impedance analyzer for their static and dynamic magnetic properties. The sintered Co2X hexaferrite shows 67.3 emu/g of saturation magnetization, 10.5 kOe of anisotropy field, and 0.03 of low magnetic loss tangent with relatively high permeability of 2.07 at 1 GHz, resulting in FOM of 69. This is the highest FOM among the reported microwave magnetic materials over the frequency range from 800 MHz to 1 GHz, which has not been previously reported. Therefore, the developed Co2X hexaferrite is suitable for antenna applications at the low‐frequency bands of mobile wireless communications.

SIMULATION OF CO-PLANAR WAVEGUIDE LIQUID CRYSTAL BASED PHASE SHIFTER

This paper discussed the design and performances of a liquid crystal phase shifter that can be used in tuning devices. Tuning devices growth with the demand in the emerging in telecommunication system. Tuning devices with smooth continuous phase shifting at low cost and compact size would be an advantage. This paper proposed a phase shifter using 5CB liquid crystal material. The advantages of using the material is the smoothness and continuity of the transitions in the phase shift. It is done by having a structure with cavity filled with the liquid crystal and applied with certain voltage that can be changed. The changes in voltage would change the applied electric field, and thus would change the permittivity of the material. The changes would affect the wave propagation and thus contribute to the phase shifting. The performance of the phase shifter was tested by means of simulation using CST Suite 2014 software. The results show that the higher the frequency, the higher the phase shift would occur. The highest FoM achieved is 68 (deg/dB) at 8 GHz. A phase shifter with smooth and continuous phase shift can be used as the feeding network in an array scanning antennas systems.

Enhanced the Dielectric and Tunable Properties of BZNT Thin Films through Adjusting Annealing Process

Bismuth zinc niobate titanium (Bi1.5Zn0.5 Nb0.5Ti1.5O7) (BZNT) thin films were deposited on PtTiSiO2Si substrates by radio frequency (rf) magnetron sputtering. The microstructure, surface morphology, stress, dielectric and tunable properties of thin films were investigated as a function of initial annealing temperature. It’s found that high initial annealing temperature increases the grain size, dielectric constant and tunability of BZNT films simultaneously and decreases the tensile stress in films. The BZNT thin film annealed from 500 °C to 700 °C shows the highest FOM value of 45.67 with the smallest dielectric loss and upper tunability.

SOI LDMOS with variable-k dielectric trench

An SOI LDMOS with a variable-k dielectric trench (VKTLDMOS) is proposed. The low-k dielectric on the top of the trench is used to sustain high voltage and ensure the smallest cell pitch while the high-k dielectric on the bottom of the trench increases the average permittivity of the trench and increases the drift doping. The SiO2 dielectric is in the middle of the high-k and low-k materials. Moreover, the SOI TLDMOS with a different k filling dielectric is also discussed. The high-k dielectric is suitable to fill a shallow and wide trench while the low-k dielectric is suitable for a deep and narrow trench. Simulation shows the VKTLDMOS has the highest FOM BV2/Rs,on compared with that of the conventional SOI TLDMOS.

Complementation SCR for RF IC ESD protection

Complementation silicon controlled rectifiers (CSCRs) with various novel layouts are designed in 0.18 µm RF CMOS process, including general CSCR, strip CSCR (SCSCR), island-strip CSCR (ISCSCR) and island-block CSCR (IBCSCR). SCSCR has highest FOM; however, the ISCSCR has lowest parasitic capacitance. Appropriate division layout of the CSCRs should be addressed to achieve a balance between active area capacitance and edge capacitance.

Materials Issues in the Application of Ferromagnetic Films in Tunable High Q VHF/UHF Devices

AbstractThin ferromagnetic films have narrow ferromagnetic resonance bandwidths, and large RF permeabilities that are attractive for tunable high Q device applications. They can also be processed at low temperatures and integrated with most RF and microwave materials. At VHF/UHF frequencies, where discrete devices can be realized, magnetic loss tangents (Q−1) less than 10−3 can be obtained, if the effects of spin resonance and eddy current losses are reduced. The material figure of merit requires a tradeoff of the permeability, and Q. The highest FOM is obtained by maximizing the magnetization, anisotropy, resistivity, and minimizing the magnetic loss. This paper discusses the interplay of these properties, and the fill factor and magnetic bias required for tunable inductors with Q>1000 in the ∼50-500 MHz range. The most promising candidates for these applications are shown to be reactively sputtered nanocrystalline films. The large resistivity, magnetization, and thickness of these films can be used to attain large film permeances, and increased shape anisotropy fields from patterned film objects. The latter eliminates the need for using a large bias magnet to achieve Q's ∼1000 at VHF/UHF operating frequencies.