Transmittance Band Research Articles

Effect of acetic acid concentration on optical properties of lead acetate based methylammonium lead iodide perovskite thin film

Abstract High absorption of perovskite thin films is crucial for efficient metal halide perovskite solar cells. In this study, methylammonium lead iodide (CH3NH3PbI3) perovskite thin films are prepared using lead (II) acetate Pb(Ac)2, acetic acid (HAc) and CH3NH3I through solution method. The effect of HAc volume (0 ml–100 ml at step size of 25 ml HAc) on optical properties and parameters of the CH3NH3PbI3 perovskite thin films developed are investigated using UV–Vis spectrophotometry and mathematical correlations. Interestingly, the increase of HAc amount to 75 ml leads to an increase in absorbance, refractive index, extinction co-efficient, dielectric properties and optical conductivity and a decrease in transmittance and optical band gaps of the CH3NH3PbI3 perovskite thin films. The optimized film is obtained at 75 ml HAc at which refractive index, film thickness and optical band gap is 1.45 at 485 nm, 355 nm and 1.47 eV, respectively. The enhanced absorption of the optimized thin film is attributable to an increase in structure ordering at HAc amount equals 75 ml. The fabricated CH3NH3PbI3 perovskite thin films have potential as ideal antireflection coatings for solar cells and optoelectronic applications.

Solar radiation transfer for an ice-covered lake in the central Asian arid climate zone

ABSTRACT Spectral albedo and light transmittance through snow, ice, and water were measured in Lake Wuliangsuhai (40°36′–41°30′N, 108°43′–108°70′E), Inner Mongolia, China, during winter 2016. Data on the weather, structure of lake ice, and geochemistry of water were also collected during the 60-day field program. The study lake is shallow (mean depth 1.0–1.5 m) with a large wetland area. Compared with polar lakes, solar elevation is higher, snow accumulation is much lower, and the ice has more sediment. The ice was all congelation ice with a mean thickness of 36.6 cm, corresponding to a mean air temperature of −9.6 °C. The mean daily broadband albedo and photosynthetically active radiation (PAR) band transmittance were 0.54 and 0.08 (bare ice), 0.74 and 0.04 (new snow), and 0.30 and 0.12 (melting period), respectively. The level of light allowed photosynthesis to occur to the bottom of the lake. The ice acted as a grey filter for the sunlight with a mean attenuation coefficient of 2.1 m−1. These results expand our knowledge of the evolution of light transfer through ice and snow cover and its role in the ecology of lakes in temperate and arid areas.

Effects of precursor concentration on the properties of magnetic iron oxide nanoparticles synthesized using brown seaweed (Sargassum crassifolium) extract

This work reports the influence of precursor concentration on the thermal and optical properties of magnetic iron oxide nanoparticles (MIONPs) synthesized via the green synthesis route. A brown seaweed (Sargassum crassifolium) extract was used to mediate the reduction of iron precursors. Ultraviolet–visible spectra showed a sharp peak between 315 and 375 nm, which corresponds to the absorbance of MIONPs. This peak intensified with an increasing concentration of iron precursors. The Fourier transform infrared spectra revealed the presence of the transmittance bands around 557 cm−1 and 565 cm−1, which corresponds to Fe-O-Fe vibrational modes suggesting the successful formation of iron oxide nanoparticles. The dynamic light scattering technique revealed that the average hydrodynamic size of the MIONPs was 31.96 ± 15.61 nm and 147.40 ± 28.48 nm. Atomic force micrograph and scanning electron micrograph both showed quasi-spherical nanostructures with sizes ranging from 40 to 215 nm. Furthermore, X-ray diffraction and thermogravimetric analyses revealed the crystallinity and thermal stability of the synthesized MIONPs, respectively. This investigation on the effect of precursor concentration provides a valuable insight for the green- mediated synthesis of MIONPs that is vital for various environmental, biomedical, and industrial application.

Review of semiconductor materials for monolithic microwave millimeter wave integrated circuits

Field of wireless communication is advancing at a very rapid rate. Some the prominent applications are wireless personal area networks, local area networks, wide area networks, satellite communication, cellular based communication, and many more. All of these applications demand implementation of high performance active and passive circuits operating at high frequency. Each type of wireless systems demands different performance requirements for the constituent circuits and systems. As an example, in cellular communication there are different requirements for base station and mobile stations systems. Base stations demands high power transceivers and small size not matters whereas as mobile station transceivers should be portable, small sized and should have low power profile. Even in a single transceiver system in which transmitter and receiver are integrated on single chip, there are different requirements for transmitter and receiver sections. In transmitter section noise, interference rejection and band selectivity are more relaxed compared to receiver section, but linearity and power efficiency are issues of concern in transmitter section. Further at high frequencies, parasitic capacitance and lead inductance make the design of circuits and systems very complex and challenging. Features as small size, low cost and high performance make the monolithic microwave/millimeter wave integrated circuit (MMIC) a very suitable option for designing circuits and systems at high frequencies. One of the specific challenges in designing an MMIC for a specified system is selection of right device and right material as per the need of circuit and system requirements. This article attempts to review some of the prominent materials used for realizing MMIC along with their characteristics advantages, disadvantages with associated active device technologies and potential application areas.

A 150-GHz Transmitter With 12-dBm Peak Output Power Using 130-nm SiGe:C BiCMOS Process

This article presents a compact 150-GHz transmitter with 12-dBm $P_{\mathrm{ sat}}$ and 17-dB conversion gain. This $D$ -band transmitter is composed of a frequency doubler, a micromixer, a two-stage $g_{m}$ -boosting power amplifier (PA), and an on-chip dielectric resonate (DR) antenna. At sub-terahertz, the output power and the gain are the limiting factors for the transmitter’s performance. In this work, $g_{m}$ -boosting topology is implemented to achieve the 17-dB gain by taking advantage of the base inductor without sacrificing the PA’s stability. The output power of the 150-GHz PA is enhanced by the proposed phase compensation method. In this proposed method, an auxiliary inductor is added for adjusting the phase difference to decrease the introduced loss from power combining and matching networks. The imbalance at the LO port is also reduced by the proposed capacitor and the resistor compensation method. From 140 to 160 GHz, the transmitter delivers more than 8-dBm output power, with the maximum $P_{\mathrm{ sat}}$ of 12 dBm at 148 GHz. This transmitter exhibits a conversion gain of 17 dB and an output 1-dB compression point ( ${\mathrm{ OP}}_{1~{\mathrm{ dB}}}$ ) of 11.4 dBm. The transmitter exhibits the highest output power, the highest ${\mathrm{ OP}}_{1~{\mathrm{ dB}}}$ , competitive conversion gain, and bandwidth among any silicon-based transmitters in $D$ -band, to the best of our knowledge.

FTIR spectroscopic investigations on the aggregation behaviour of N,N,N′,N′-tetraoctyldiglycolamide and N,N-dioctylhydroxyacetamide in n-dodecane during the extraction of Nd(III) from nitric acid medium

Fourier Transform Infra Red (FTIR) spectroscopy is an excellent tool for probing the co-ordination chemistry of the solvent extracted metal complexes in organic phase. The organic phase containing tetraoctyldiglycolamide (TODGA) and N,N-dioctylhydroxyacetamide (DOHyA) ligands dissolved n-dodecane was employed for the extraction of Nd(III) from nitric acid medium. The extracted organic phase was probed by FTIR spectroscopy to understand the coordination chemistry and aggregation behaviour of Nd(III)-ligand complex in the binary solution. The results were compared with those obtained in the individual solvent system. The extraction of Nd(III) and nitric acid in organic phase was accompanied by shifting and broadening of amidic carbonyl stretching bands of TODGA and DOHyA, and the degree of shift or broadening was dependent on the amount of Nd(III) or nitric acid loaded in organic phase. Near complete shift of amidic carbonyl transmittance bands from 1660 cm−1 to 1610 cm−1 was observed prior to the undesirable event known as organic phase splitting. The results showed the possibility of employing the FTIR spectroscopic technique for understanding the extraction and for the prevention of organic phase splitting during the course of solvent extraction.

Enhanced electrochemical property of SILAR-deposited Mn3O4 thin films decorated on graphene

Manganese oxide and manganese oxide decorated on graphene thin films were successfully synthesized and decorated on graphene via successive ionic layer adsorption and reaction (SILAR) method. The morphological, elemental, structural, optical and electrochemical properties of the deposited films were respectively studied using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX, or EDS), X-ray diffractometry (XRD), UV–vis spectrophotometry and a 3-electrode potentiostat. Decorating the manganese oxide film on graphene improved the morphological, structural, optical, and electrochemical features of the deposited films. SEM image revealed irregularly fused capsule-like nanoparticles, EDX spectra confirmed the elemental composition of the films while the structure of the film improved from amorphous to crystalline after decorating on graphene. Optical results showed improved the transmittance and optical band gap values of the films upon decoration on the graphene. Electrochemical studies showed good cyclic voltammograms and a recorded maximum specific capacitance value of 194Fg−1. The films find potential application in electrochemical storage devices and optical devices.

Fabrication of Novel (PMMA-Al2O3/Ag) Nanocomposites and its Structural and Optical Properties for Lightweight and Low Cost Electronics Applications

In this paper, preparation new type of nanocomposites may be considered as promising materials for different electronic and optical applications such as solar cells, sensors, electronics gates, transistors, lens, lasers ..etc . The nanocomposites were prepared with different concentrations of polymethylmethacrylate (PMMA), aluminum oxide (Al2O3) nanoparticles and of silver (Ag) nanoparticles are (PMMA0.98-(Al2O3)0.02)1-x/Agx where x=.0, 0.02, 0.04 and 0.06. The structural and optical properties of (PMMA-Al2O3-Ag) nanocomposites have been studied. The optical properties of nanocomposites were examined in wavelength range (220-820)nm. The results of optical properties for (PMMA-Al2O3-Ag) nanocomposites showed that the absorbance, absorption coefficient, extinction coefficient, refractive index, imaginary and real dielectric constants and optical conductivity of (PMMA-Al2O3) nanocomposites are increased with the increase in silver nanoparticles concentrations while the transmittance and energy band gap decrease with increase of the Ag nanoparticles concentrations. The results showed that the (PMMA-Al2O3-Ag) nanocomposites are promising for different optoelectronics applications.

Optical and structure properties of CdTe/CdS films under influence of both CdCl2 heat treatment and (O2 + Ar) atmosphere

Thin films of CdTe/CdS were prepared using the thermal evaporation technique with pressure 2 × 10−5 mbar on substrate from glass. The thickness of CdCl2 layer around 150 nm was deposited making as-deposited CdTe/CdS films. The films covered by cadmium chloride (CdCl2) layer were annealed in atmosphere of (O2 + Ar) at different temperatures of 400 °C, 450 °C and 480 °C for 15 min. The effect of CdCl2 as a top layer on morphological, structural and optical properties was studied, and the results were compared with as-deposited films and also with (O2 + Ar) annealing process. The refractive index in whole wavelength and film thickness was estimated by Cauchy dispersion relation and Swanepoel's envelope method, respectively. Furthermore, many optical parameters such as transmittance, absorbance, reflectance, and optical band gap, Urbach energy, film thickness, electronic polarizability, lattice dielectric constant were calculated also in this study. The heat treatment of our films with depositing CdCl2 layer in (O2 + Ar) flow lowered the energy gap which led CdTe/CdS films to be a candidate to work in thin-film solar cells as an absorber layer.

Preparation and Properties of ZnS‐Reinforced ZnS/ZnSe Composites

AbstractZnS‐reinforced ZnS/ZnSe composites are prepared by chemical vapor deposition. Scanning electron microscope, transmittance, and bending strength are used to characterize the samples. The schematic diagram of the transmittance model of the double‐layer composite window is used to calculate the theoretical transmittance, and the measured value of the transmittance of ZnS/ZnSe composite material is in good agreement with the calculated value. The effects of interface layer on the optical and mechanical properties of materials are studied in detail. It is found that the interface can affect the transmittance of the composites, but it still maintains a high transmittance, and the influence of interface layer on the transmittance of visible band is more serious than that of infrared band. Moreover, the mechanical properties of the new composite material are significantly improved (35%).

Up to 98.2% super transmittance and precise modification of wavelength band in vein-like Ag in ITO/Ag/AZO sandwich structure

High transmittance and low resistance ITO/Ag/AZO (IAA) sandwich structures were fabricated as transparent electrodes through a combination of the pulsed laser deposition (PLD) and the RF magnetron sputtering techniques. The Ag in the middle layer forms vein-like network in the IAA structure, resulting in improved electrical conduction. The maximum transmission in different wavelength bands of the IAA structure was achieved by changing the thickness of each layer. The highest transmittance of 98.24% was observed at 486 nm for the structure with Ag-layer thickness of 8 nm. By optimizing the layer thicknesses of the fabricated structure, the lowest sheet resistance of 5.8 Ω/□ with an average transmittance of 90.28% in the visible region was obtained for the ITO (35 nm)/Ag (10 nm)/AZO (35 nm) electrode. The transmittance wavelength band of the IAA structure was modified precisely by controlling the layer thickness of the ITO and AZO films. The highest figure of merit (FOM) value of 1.21 × 10−1 Ω−1 was obtained for the ITO (35 nm)/Ag (10 nm)/AZO (35 nm) electrode, which suggests a high potential of these electrodes for application in the photovoltaic devices.

Electrodeposition of oriented ZnO nanorods by two-steps potentiostatic electrolysis: Effect of seed layer time

We studied the effect of seed layer deposition time on the growth of ZnO nanorods by using potentiostatic electrolysis. Microstructural, optical and photoelectrochemical responses of ZnO nanorods were determined from XRD, FE-SEM, UV–Vis spectroscopy, and Mott–Schottky measurements. Changes in seed layer time, crystallinity, diameter and density of ZnO nanorods were examined. The results show that the sample deposited with the seed layer time of 60 s, has a good crystallinity and preferred orientation along the plane (002) and high nanorod density with smaller diameter size. The sample showed an enhanced photoelectrochemical response with low carrier density, compared to other ZnO samples. The optical measurements showed high transmittance and direct band gap of around 3.24 eV. The nanostructured ZnO deposited in this work is a promising candidate for photocatalytic and photovoltaic applications.

Composite titanium oxide nanocolumnar thin films for low-emissivity coating

The TiOX thin films were grown on the glass substrate for the low-e film applications by direct-current magnetron sputtering methods. The composite nature of dielectric and metallic phases including Ti2O3, TiO2 and amorphous TiOx were identified from the comparative study of x-ray diffraction and Raman spectroscopy. The coalescent nanocolumnar structure revealed from scanning electron microscopy is believed to be responsible for the absence of the interference in the transmission. Most interestingly, the narrow transmittance bands from the films were observed in the visible region, especially in the violet-blue-green color portion, which could be ideal for the applications of narrow band-pass filters or red/infrared reflectors.

Study of structural, optical and enhanced multiferroic properties of Ni doped BFO thin films synthesized by sol-gel method

Abstract Pure and nickel (Ni) doped bismuth ferrite (BiFeO3, BFO) thin films were successfully deposited on the SnO2:F (FTO)/glass substrate by a sol-gel method. The structure, phase evolution, chemical composition, surface element chemical states, surface morphology, multiferroic and optical properties were systematically investigated. The structural analyses using XRD and Raman techniques revealed that Ni doping induced a structure transition from rhombohedral toward orthorhombic or tetragonal structure. The surface element chemical states examined by XPS demostrated that Ni doping resulted in the increase of oxygen vacancies while decrease of Fe2+ concentration. SEM images demonstrated that Ni doping impacted the grain growth mechanism and the average grain size increased with increase of Ni doping. EDS analysis further confirmed the element composition with presence of Ni element in the Ni doped BFO thin films. The leakage current density of Ni doped BFO thin films was observed to increase with increase of Ni doping due to the higher oxygen vacancies. An enhanced ferroelectric and piezoelectric properties were obtained in the BFO thin film with Ni doping x = 0.10, giving a high remnant polarization (2Pr) of 22.95 μc/cm2 with a coercive field (2Ec) of 728.24 kV/cm and high piezoelectric coefficient (d33,eff) of 37.76 p.m./V. Meanwhile, the magnetization measurement revealed that Ni doped BFO thin films showed an enhanced magnetization, compared to pure BFO thin film. The highest saturation of 2.85 emu/cm3 under a magnetic field of 10 k Oe is also observed in BFO thin film with Ni doping x = 0.10. The transmittance and optical band gap decreased with increase of Ni doping and when Ni doping is x = 0.10, the lowest band gap of 2.46 eV was observed.

An ISM Band High-Linear Current-Reuse Up-Conversion Mixer With Built-in-Self-Calibration for LOFT and I/Q Imbalance

This brief presents a high-linear current-reuse upconversion mixer with built-in-self-calibration for LO feed through (LOFT) and I/Q imbalance for the 2.4GHz ISM band transmitter. Exploiting the negative feedback loop and the saturated switches biased by the current bleeding, third-order intermodulation (IM3) products are eliminated. Based on the fully differential push-pull OP-AMP and current mirror, the current-reuse input transconductance with a boosted gain is achieved. LOFT and I/Q imbalance calibrations are carried out utilizing two fully-integrated auto-calibration loops with the auto-zero comparator and the low noise envelope detector, respectively. Fabricated in 40 nm LP CMOS technology, the mixer shows 15.02 dBm OIP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and -1.80 dBm OP1dB while consuming 12.75 mW from 1.1 V power supply for 4.17 dB gain. Along with the third-order filter, the up-conversion mixer achieves >40 dBc LO suppression ration (LSR) and 50.6 dBc image rejection ration (IMRR) within ±2 dB deviation among 10 MHz bandwidth, thanks to the two calibration loops.

A 0.5 nJ/b 60 GHz ultra wideband transmitter for short range wireless sensor network applications

AbstractA novel monolithic microwave integrated circuit (MMIC) design of ultra wide band (UWB) transmitter at 60 GHz with simple architecture and high‐range resolution ability is presented in this paper. Implemented with 0.1 μm 100 GHz GaAs positive channel high electron mobility transistor (PHEMT) technology offered by OMMIC, the transmitter comprises a millimeter wave oscillator, a buffer amplifier (BA), a medium power amplifier (MPA) and two UWB Pulse Generators (UWBPG). For the sake of the goal on reducing the entire transmitter consumption, the oscillator is controlled by one UWBPG and another UWBPG drives the BA and MPA simultaneously. The transmitter has infinite isolation level to minimize the interference with neighboring devices. For a pulse repetitive time of 5 ns, pulse width of 500 ps and supply voltage of 3 V, the transmitter consumes only 101 mW and has a peak transmit power of 9.2 dBm corresponding to 0.5 nJ per pulse energy consumption, which is suitable for future short range wireless sensor network (WSN) applications.

Structural, Optical and Electrical Properties of PVA/PEO/SnO2 New Nanocomposites for Flexible Devices

Fabrication of polyvinyl alcohol (PVA)–polyethylene oxide (PEO) blend doped with tin dioxide (SnO2) nanocomposites has been investigated for flexible electrical and optical applications. The prepared nanocomposites have low cost, lightweight, flexible, high corrosion resistance, good optical and electrical properties. These properties of fabricated nanocomposites make it useful for different optoelectronics applications such as: sensors, solar cells, transistors, diodes, capacitors, energy storage etc. The structural, optical and electrical properties of (PVA–PEO–SnO2) nanocomposites have been studied. The experimental results of optical properties for (PVA–PEO–SnO2) nanocomposites showed that the nanocomposites have higher absorbance in UV region at wavelength range (200–280) nm. This behavior makes the nanocomposites may be used for optoelectronics applications. The absorbance, absorption coefficient, extinction coefficient, refractive index, real and imaginary dielectric constants and optical conductivity of polymer blend are increased with the increase in SnO2 nanoparticles concentrations while the transmittance and energy band gap are decreased with the increase in SnO2 nanoparticles concentrations. The decrease in energy band gap is useful for different optoelectronics devices industries. Also, the results showed that the dielectric constant and dielectric loss decrease while the conductivity increases with the increase in frequency. The dielectric constant, dielectric loss and conductivity are increased with the increase in SnO2 nanoparticles concentrations. The electrical properties showed that the (PVA–PEO–SnO2) nanocomposites have good dielectric parameters which it may be used for different electronics applications.

Lower Cost and Higher UV-Absorption of Polyvinyl Alcohol/ Silica Nanocomposites For Potential Applications

Films of (polyvinyl alcohol- silicon dioxide) nanocomposites were prepared for UV- shielding with low cost, low weight and excellent anti-UV properties. Studying the structural and optical properties of PVA/SiO2 nanocomposites have been investigated. The experimental results showed that the absorbance (A), absorption coefficient (), extinction coefficient (K), refractive index (n), real (e1) and imaginary (e2) parts of dielectric constants and optical conductivity (σop) of PVA are increased with increasing of the SiO2 concentrations. The transmittance (T) and energy band gap (Eg) decrease as a SiO2 concentrations increase. Also, te results showed that (PVA-SiO2) nanocomposites can be used for flexible solar cells, diodes and transistors applications.

Porous starch citrate biopolymer for controlled release of carbofuran in the management of root knot nematode Meloidogyne incognita

The undesirable environmental impacts of inappropriate application of pesticides have brought about research into new matrices for controlled release of pesticides. Porous starch citrate biopolymer was designed for the release of carbofuran in this experiment and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermo-Gravimetric Analysis (TGA) for functional group, surface morphology and thermal stability properties respectively. The SEM revealed highly stabilized porous starch citrate biopolymers with porous structures and gradients suitable for controlled release studies. The transmittance bands at 3347, 1714 and 1073 cm−1 for OH, CO and COC stretching vibrations further confirms the successful synthesis of the biopolymer. TGA showed an increase in the thermal stability after citric acid modification with one-step decomposition from 290 ᵒC to 500 ᵒC. From Korsemeyer-Peppas model, the carbofuran-porous starch citrate (CBFN/PRS/STH/CTRT) followed a lower diffusion release model with gradual increment in all the quantity of carbofuran loaded. An accelerated rate of diffusion percentage was seen in direct application of carbofuran. Egg hatch and mortality of juveniles were recorded on daily basis for seven days. Direct application of carbofuran (CBFN/DRT) and carbofuran-porous starch citrate biopolymer gave the best results with significant (p < 0.05) reduction in egg hatch and higher percentage mortality. The rate of release of carbofuran from the starch citrate bio polymer matrix was significantly lower than the direct application, and in spite of the slow rate of release, higher juvenile mortality and reduction in egg hatch was achieved.

Structural and optical properties of nanocrystalline MoO3 thin films grown by thermal oxidation of sputtered molybdenum films

Nanocrystalline MoO3 films were synthesized using thermal oxidation of molybdenum films deposited on quartz substrates by DC magnetron sputtering at different sputtering powers and times. The structural, morphological and optical properties of MoO3 films were studied by XRD, AFM, FESEM, RBS, and spectrophotometry. XRD patterns showed that, upon thermal oxidation the amorphous Mo films transformed to polycrystalline α-MoO3. The average crystallite size varied between 23 and 49 nm. AFM and FESEM images exhibited that the surface morphology of the films effectively influenced by sputtering parameters. The variation of transmittance and optical band gap with the deposition parameters were also discussed.