Showing papers in "Journal of Materials Science: Materials in Electronics in 2014"
TL;DR: In this paper, Nanocrystalline SnO2 particles with the rutile structure have been successfully synthesized by a novel microwave irradiation method, which requires less reaction time and low temperature.
Abstract: Nanocrystalline SnO2 particles with the rutile structure have been successfully synthesized by a novel microwave irradiation method. This process requires less reaction time and low temperature. Transmission electron microscopy studies show that SnO2 particles are in spherical shape with size about 25–30 nm. Selected area electron diffraction pattern confirms single crystalline nature of the SnO2. UV–Vis spectrometer was carried out to study the optical properties and estimated band gap energy of SnO2 particles is 3.55 eV. In Fourier transform infrared study, a defined peak at around 615 cm−1 is observed due to Sn–O vibration. Frequency dependent dielectric anomaly is observed in SnO2 nanoparticles at low temperature. It is found that the value of dielectric constant of SnO2 particles at 10 kHz is found to be 777.5. It systematically decreases with increasing frequency whereas increases with increasing temperature. Further, the prepared samples were characterized by Photoluminescence spectroscopy and energy dispersive spectroscopy.
139 citations
TL;DR: In this article, the authors present a deep insight into different organic/inorganic materials used for the dielectric layer, electrodes and substrate for thin film transistors (TFTs).
Abstract: This paper reviews recent advancements in the field of organic electronics. Performance of p- and n-type conducting polymers and small molecule organic semiconductors is presented primarily in terms of mobility and current on/off ratio. Moreover, it presents a deep insight into different organic/inorganic materials used for the dielectric layer, electrodes and substrate for thin film transistors (TFTs). The electrical characteristics and performance parameters of single and dual gate structures are compared. In addition, performance dependence of organic TFT (OTFT) is discussed on the basis of contact resistance, channel length and thickness of the active layer. The paper thoroughly discusses several important applications of OTFTs including inverter, organic static random access memory, radio frequency identification tag and DNA sensors. It also includes several limitations and future prospects of organic electronics technology.
125 citations
TL;DR: In this paper, the effect of annealing temperature on the structural and optical properties of titania nanoparticles was investigated by means of X-ray diffraction, Raman spectroscopy, UV-visible spectrograph, and photoluminescence.
Abstract: Titania nanoparticles have been prepared using different surfactants such as, acetic acid (AA), oleic acid (OA), oley amine (OM), and a mixture of OA + OM at room temperature by sol–gel method. TiO2 nanoparticles were collected by centrifugation of the precipitate obtained during gel formation. The collected samples were annealed at 550 and 950 °C to study the effect of annealing temperature on the structural and optical properties. The crystal structure and optical properties of titania nanoparticle is investigated by means of X-ray diffraction, Raman spectroscopy, UV–visible spectroscopy, and photoluminescence. After heat treatment at 950 °C, the mixed rutile and anatase phase of TiO2 was revealed for the sample prepared with AA, whereas pure rutile phase was observed for the sample prepared in presence of OA, OM and the mixture of OA + OM. The energy band gap and transmittance of measured for titania nanoparticles was found to be systematically reduced with increase in annealing temperature for each surfactant. The ideality factor decreases with increase in annealing temperature for all surfactants could be related to the voltage dependence of the standard deviation of the distribution of barrier heights.
107 citations
TL;DR: In this paper, the effect of synthesis route on the multifunctional properties of multiferroic BiFeO3 powders were prepared by conventional solid-state-reaction and sol-gel route.
Abstract: In this article, we studied the effect of synthesis route on the multifunctional properties of multiferroic BiFeO3. BiFeO3 powders were prepared by conventional solid-state-reaction and sol–gel route. X-ray diffraction (XRD) patterns for these samples were collected at different stages of synthesis to analyze the phase purity of the formation. The XRD patterns reveal that sample prepared by sol–gel route attains the low temperature phase formation as compared to the solid state route. Rietveld refinement has been performed for these samples and lattice parameters, cell volume bond length etc. have been calculated from XRD patterns. Phonon modes were studied by Fourier transform infrared spectroscopy measurements and bond length calculated from XRD shows the good agreement with the bond length calculated from IR spectra. UV–visible spectra showed that BFO nanoparticles exhibit absorption peak at wavelength ~521 nm and band gap is more for the sample prepared by sol–gel route than solid state. The room temperature (RT) magnetic hysteresis (M–H) curve shows the large value magnetization in the sample prepared by sol–gel route in comparison to the sample prepared by solid state route. Similar behaviour is seen in the P–E hysteresis curve. Room temperature dielectric properties of these samples revealed that there is dispersion in the low frequency range that shows normal dielectric characteristics.
81 citations
TL;DR: In this paper, the crystal structure and particle morphology of high-saturated red aluminate phosphors were investigated by X-ray diffraction, scanning electron microscopy and their photoluminescence were studied by the excitation and emission spectra.
Abstract: High-saturated red aluminate phosphors SrMgAl10O17 doped with Mn4+ ions were prepared by solid-state reaction at 1,400 °C. The crystal structure and particle morphology of SrMgAl10O17:Mn4+ phosphors were investigated by X-ray diffraction, scanning electron microscopy and their photoluminescence were studied by the excitation and emission spectra. The excitation spectrum of samples showed two broad absorption bands ranging from 250 to 480 nm, which indicated that SrMgAl10O17:Mn4+ could be effectively excited by both near-ultraviolet light and the commercially available blue light of light-emitting diode chips. Simultaneously, the emission spectrum exhibited two sharp peaks (651 and 662 nm) in the deep-red region. It was found that the quenching concentration of Mn4+ in phosphor was 1.5 mol%. In the end, the effects of doping ions, M (Li+, Na+, K+, Cl−) ions, on the luminescent properties of SrMgAl10O17:Mn4+ were investigated, respectively. The results suggested that all of Li+, Na+, and Cl− could significantly improve the luminescent properties of SrMgAl10O17:Mn4+, and the phosphor SrMgAl10O17:Mn4+, M (M = Li+, Na+, Cl−) was expected to be used as a red phosphor in warm white light emitting diode.
70 citations
TL;DR: In this article, the authors used X-ray diffraction and Raman spectroscopy to determine the crystal structure of pyrochlore La2Zr2O7 (Zr0.9Ti0.1)1−x/4O3 (BLZT) ceramics.
Abstract: Ba1−xLax (Zr0.9Ti0.1)1−x/4O3 (BLZT) ceramics with x = 0.02 (BLZT-1), 0.04 (BLZT-2), 0.06 (BLZT-3) and 0.08 (BLZT-4) were prepared by a solid-state reaction route. Crystal structure of the BLZT ceramics was determined using X-ray diffraction and Raman spectroscopy. While the ceramics for x ≤ 0.04 are pure phase with cubic perovskite structure, pyrochlore La2Zr2O7 appears in the samples with x = 0.06 and 0.08. Dielectric properties as function of temperature and frequency showed more than one dielectric anomaly were found at high temperatures during heating but they weakened or disappeared during cooling. Both dielectric relaxation and electrical conductivity were taken into account in point defect mechanism. The double-ionized and short-range hopping of oxygen vacancy should be mainly responsible for the dielectric anomalies and conduction behavior. Activation energy of conductivity E
con
is lower than half of the band gap E
g
obtained by UV–Vis spectroscopy, which results from emergency of oxygen vacancies. In visible light region, the ceramics show a strong absorption with band gap of about 3.57 eV.
65 citations
TL;DR: In this paper, the optical, structural, thermal, zeta potential and electrical properties of multi-shaped AgNPs were studied for their optical response and TEM, and the crystallite size of nanoparticles and strain of the sample was found to be around 39 nm and 2.3 × 10−1.
Abstract: Silver nanoparticles (AgNPs) have been synthesized using maltose as reducing agent and microwave heating as reaction initiator. The nanoparticles are studied for their optical, structural, thermal, zeta potential and electrical properties. The synthesis protocol used is fast and resulted in the formation of multi-shaped AgNPs as indicated by their optical response and TEM. The crystallite size of nanoparticles and strain of the sample was found to be around 39 nm, and 2.3 × 10−1, respectively, as calculated from XRD data. Zeta potential and electrical response both showed almost threefold increase for multi-shaped as compared to isotropic nanoparticles.
61 citations
TL;DR: In this paper, the authors used helium ion beam induced cobalt nanowire deposition using dicobalt octacarbonyl (Co2(CO)8) as a precursor.
Abstract: Helium ion beam induced cobalt nanowire deposition using dicobalt octacarbonyl (Co2(CO)8) as a precursor is described. 10 nm wide metal lines were fabricated with good repeatability and extremely high purity. The metal lines were deposited on electrical test structures to determine the nanowire resistivity and contact resistance. Measurements reveal that these metal lines have 50–100 μΩ-cm resistivity. The contact resistance of a Co line on a gold pad is 15 Ω with a 0.14 × 1.4 μm contact area. The resulting metal deposit size was determined by helium ion microscopy (HIM) because of its high imaging resolution, and further characterized by high resolution transmission electron microscopy (HR-TEM) and electron energy-loss spectroscopy (EELS). HR-TEM images reveal that these metal lines are composed of 6 ± 2 nm cobalt crystallite grains; and EELS analysis shows that no measurable carbon signal was observed. Single-line and multiple-line patterns were prepared to examine proximity effects around the metal line depositions. Both HIM imaging and electrical measurements of the patterns verify that the collateral proximity deposition between individual lines can be minimized. Finally, factors determining the ultimate line width achievable with the He ion beam are discussed.
61 citations
TL;DR: In this paper, a single beam open aperture Z-scan technique using a continuous wave He-Ne laser at the wavelength of 632.8 nm was used to measure the absorption coefficient of Brilliant Green solution.
Abstract: Laser induced nonlinear absorption coefficient of Brilliant Green solution was measured by single beam open aperture Z-scan technique using a continuous wave He–Ne laser at the wavelength of 632.8 nm. It was found that the material exhibits multiphoton absorption type optical nonlinearity. Significant optical nonlinearity is an indicative that Brilliant Green dye is prominent material for low power nonlinear applications. Ultraviolet–visible and photoluminescence (PL) spectra of Brilliant Green solutions are also recorded. A strong linear absorption band with a peak at 625 nm has been observed, while the PL intensity was found to decrease due to quenching effect on increasing the concentration.
59 citations
TL;DR: In this article, a ternary electromagnetic wave absorbing materials were prepared by in situ polymerization of aniline monomer on the surface of Fe3O4-reduced graphene oxide-polyaniline nanocomposites.
Abstract: Fe3O4-reduced graphene oxide-polyaniline (Fe3O4–RGO–PANI) ternary electromagnetic wave absorbing materials were prepared by in situ polymerization of aniline monomer on the surface of Fe3O4–RGO nanocomposites. The morphology, structure and other physical properties of the nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, vibration sample magnetism, etc. The electromagnetic wave absorbing properties of composite materials were measured by using a vector network analyzer. The PANI–Fe3O4–RGO nanocomposites demonstrated that the maximum reflection loss was −36.5 dB at 7.4 GHz with a thickness of 4.5 mm and the absorption bandwidth with the reflection loss below −10 dB was up to 12.0 GHz with a thickness in the range of 2.5–5.0 mm, suggesting that the microwave absorption properties and the absorption bandwidth were greatly enhanced by coating with polyaniline (PANI). The strong absorption characteristics of PANI–Fe3O4–RGO ternary composites indicated their potential application as the electromagnetic wave absorbing material.
57 citations
TL;DR: In this paper, the energy-storage properties of lead-free antiferroelectric ceramics were investigated by two-step sintering method, showing a typical double hysteresis loops, accompanied by a large energy density.
Abstract: The energy-storage properties of SrTiO3-doped (15, 20, 25, and 30 mol%) 0.80Bi1/2Na1/2TiO3–0.20Bi1/2K1/2TiO3 lead-free antiferroelectric ceramics were investigated by two-step sintering method. The ceramics with higher SrTiO3 content had smaller grain sizes and a more homogeneous distribution. About 25 mol% SrTiO3 doping induced antiferroelectric properties, showing a typical double hysteresis loops, accompanied by a large energy density. The first sintering temperature of the ceramics had main impact on the relative density, and the high relative density possessed large external breakdown strength. The optimum electrical performances with a low remanent polarization (Pr = 1.9 μC/cm2), a low coercive field (Ec = 1.7 kV/cm) and a large energy density (W = 0.97 J/cm3) at 10 Hz were obtained at 1,190 °C for a SrTiO3 content of 25 mol%.
TL;DR: In this article, the authors summarized the dielectric behavior of perovskite glass ceramics such as BaTiO3, SrTiO2, PbTiO1, Ba,Sr)TiO 3 and (Pb,SiSiO2).
Abstract: The recent developments of energy storage devices are concerned with larger energy storage ability, low loss and good temperature stability. It has a great technological importance in engineering science. The dielectric materials like ceramics and glass ceramics have great interest in electronic ceramic industry due to above concern. The ceramic dielectrics are used as a capacitive element in electronic circuits. The perovskite glass ceramics have very high dielectric constant and low dielectric loss. The high dielectric constant in glass ceramics is attributed to space charge polarization. In order to produce glass ceramics of high dielectric constant, barium titanate glass ceramics is the first discovered ferroelectric perovskite. In this review article, we are summarizing the dielectric behavior of perovskite glass ceramics such as BaTiO3, SrTiO3, PbTiO3, (Ba,Sr)TiO3 and (Pb,Sr)TiO3.
TL;DR: Cobalt-doped Zinc sulfide (ZnS) nanoparticles were prepared by a simple chemical method using alkyl hydroxyl ethyl dimethyl ammonium chloride (YH) as capping agent.
Abstract: Cobalt-doped Zinc sulfide (ZnS) nanoparticles were prepared by a simple chemical method using alkyl hydroxyl ethyl dimethyl ammonium chloride (YH) as capping agent The structural and optical properties of prepared cobalt-doped ZnS nanoparticles have been characterized X-ray diffraction patterns and transmission electron microscope images reveal pure cubic ZnS phase with size of about 5–2 nm for all cobalt-doped ZnS nanoparticles The lattice constant of the samples decreases slightly by the introduction of Co2+ The absorption edge of the ZnS:Co2+ nanoparticles is blue-shifted as compared with that of bulk ZnS, indicating the quantum confinement effect The photoluminescence emission band exhibits a blue shift for Co-doped ZnS nanoparticles as compared to the ZnS nanoparticles
TL;DR: In this article, the preparation of α-Fe2O3 nanoparticles using curcuma and tea leaves extract is reported, and the as-prepared samples have well-crystallized rhombohedral structure.
Abstract: In this study, the preparation of α-Fe2O3 nanoparticles using curcuma and tea leaves extract are reported. The curcuma and tea leaves are acted as a reductant and stabilizer. The crystal structure and particle size of the as-synthesized materials were measured through X-ray diffraction. X-ray diffraction patterns revealed that the as-prepared samples were α-Fe2O3 nanoparticles with well-crystallized rhombohedral structure and the crystallite sizes of the α-Fe2O3 nanoparticles are 4 and 5 nm. Scanning electron microscopy images showed that the prepared samples have spherical shape. The purity and properties of the as-synthesized α-Fe2O3 nanoparticles were measured by Raman spectroscopy. The chemical compositions of the as-prepared α-Fe2O3 nanoparticles have been analyzed by Fourier transform infrared spectroscopy. The absorption edge of the α-Fe2O3 nanoparticles are 561 and 551 nm. The photocatalytic activity of the α-Fe2O3 nanoparticles was measured by degradation of methylene orange and the α-Fe2O3 nanoparticles showed the excellent photocatalytic performance.
TL;DR: In this article, the authors combined the finite element method and Garofalo-Arrheninus creep model to evaluate the reliability of different lead-free solder joints (snAgCu, SnAg, SnSb and SnZn) and SnPb solder joints in chip scale package (CSP) 14 × 14 device under thermal cyclic loading.
Abstract: Finite element method and Garofalo–Arrheninus creep model were combined and used to evaluate the reliability of different lead-free solder joints (SnAgCu, SnAg, SnSb and SnZn) and SnPb solder joints in chip scale package (CSP) 14 × 14 device under thermal cyclic loading. The results show that von Mises stress and equivalent creep strain in each of the four lead-free solder joints and SnPb solder joints were strongly different, increasing in the order SnPb < SnAg < SnSb < SnZn < SnAgCu. It is found that maximum stress–strain concentrates on the top-surface of corner solder joints in the CSP device for all solder joints, and SnAgCu solder joints shows the highest fatigue life among those five kinds of solder joints.
TL;DR: In this article, the effect of Bi, Ni concentration on the microstructure and interfacial intermetallic compounds of low-Ag Sn 0.7Ag 0.5Cu (SAC0705)/Cu and Sn 3 Ag 0.6Sn5 (SSA305)/Cu was investigated.
Abstract: This paper investigated the effect of Bi, Ni concentration on the microstructure and interfacial intermetallic compounds of low-Ag Sn–0.7Ag–0.5Cu–xBi–yNi/Cu solder joints by comparing with Sn–0.7Ag–0.5Cu (SAC0705)/Cu and Sn–3Ag–0.5Cu (SAC305)/Cu. Meanwhile, the shear behavior of the solder joints at both the bulk solder and soldering interface with various Bi, Ni content were also studied. Experimental results indicated that SAC0705–3.5Bi showed coarse microstructure due to the excessive growth of β-Sn dendritic crystal, which can be obviously suppressed by small amount of Ni element addition. Needle-like (Cu, Ni)6Sn5 appeared in the bulk solder of SAC–Bi–Ni/Cu, instead of the pipe-like Cu6Sn5 in SAC/Cu. Compare with SAC0705/Cu and SAC305/Cu, SAC–Bi–Ni/Cu showed higher shear strength at both the bulk solder and soldering interface. The increase of Bi content significantly increased the shear strength of Sn–0.7Ag–0.5Cu–xBi–yNi/Cu solder joints at the soldering interface. Brittle fracture appeared in the bulk solder of Sn–0.7Ag–0.5Cu–3.5Bi–0.05Ni/Cu solder joint. But this brittle failure can be suppressed by increasing the concentration of Ni in the solder alloys.
TL;DR: In this article, the authors reported the preparation of cadmium sulphide (CdS) nanoflakes at room temperature by simple arrested precipitation method, which was characterized by various techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform-infrared spectrography, and UV-Visible spectrophotometer.
Abstract: Herein, we report, preparation of cadmium sulphide (CdS) nanoflakes at room temperature by simple arrested precipitation method. The synthesized CdS nanoflakes were characterized by various techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform-infrared spectroscopy, and UV–Visible spectrophotometer. Nanoflakes of CdS were found to be a mixed-phases composed of cubic and hexagonal with average crystallite size of 20 nm. Surface morphology of CdS seems to be nanoflakes. The absorption spectrum was slightly shifted to blue region as compared to the bulk, this indicates that synthesized material is smaller in size. The band gap energy was found to be 2.48 eV. The photocatalytic results reveals that CdS nanoflakes exhibits excellent photocatalytic performance for methyl orange (20 ppm) degradation, under sunlight and UV within 120 min (83 and 95 % respectively).
TL;DR: In this article, the electrochemical, morphological, structural and optical properties of the zinc oxide (AZO) thin films were investigated in terms of different Al concentration in the starting solution, and it was found that the carrier density of AZO thin films varied between −3.11 and −5.5 at.
Abstract: Al-doped zinc oxide (AZO) thin films are prepared on polycrystalline fluorine-doped tin oxide-coated conducting glass substrates from nitrates baths by the electrodeposition process at 70 °C. The electrochemical, morphological, structural and optical properties of the AZO thin films were investigated in terms of different Al concentration in the starting solution. It was found that the carrier density of AZO thin films varied between −3.11 and −5.56 × 1020 cm−3 when the Al concentration was between 0 and 5 at.%. Atomic force microscopy images reveal that the concentration of Al has a very significant influence on the surface morphology and roughness of thin AZO. X-ray diffraction spectra demonstrate preferential (002) crystallographic orientation having c-axis perpendicular to the surface of the substrate and average crystallites size of the films was about 33–54 nm. With increasing Al doping, AZO films have a strong improved crystalline quality. As compared to pure ZnO, Al-doped ZnO exhibited lower crystallinity and there is a shift in the (002) diffraction peak to higher angles. Due to the doping of Al of any concentration, the films were found to be showing >80 % transparency. As Al concentration increased the optical band gap was also found to be increase from 3.22 to 3.47 eV. The room-temperature photoluminescence spectra indicated that the introduction of Al can improve the intensity of ultraviolet (UV) emission, thus suggesting its greater prospects in UV optoelectronic devices. A detailed comparison and apprehension of electrochemical, optical and structural properties of ZnO and ZnO:Al thin films is done for the determination of optimum concentration of Al doping.
TL;DR: In this paper, the microwave absorption properties of SiCNWs/paraffin composites were investigated over 2-14 GHz and showed that the optimal reflection loss can reach −48.1dB at 13.52 GHz when the thickness of the match is only 1.9mm.
Abstract: Bamboo-like and cubic single-crystalline silicon carbide nanowhiskers (SiCNWs) were synthesized using multiwalled carbon nanotube via a process of calcination in the molten-salt circumstance. The system was heated to 1,250 °C and maintained for 6 h in argon atmosphere, and obtained the sample. The as-prepared sample was characterized by a series of techniques. Especially, the microwave absorption properties of SiCNWs/paraffin composites (30 wt%) were investigated over 2–14 GHz. The result shows the optimal reflection loss can reach −48.1 dB at 13.52 GHz when the thickness of the match is only 1.9 mm. The excellent microwave absorption properties of the SiCNWs/paraffin composites due to the dielectric loss would make it as a promising candidate for the application of absorbing materials. In addition, a possible growth mechanism of SiCNWs was also discussed.
TL;DR: In this article, the obtained nanospheres have been structurally characterized by XRD which confirms the single crystalline orthorhombic structure and structural information of the nanosphere was also confirmed from the Raman spectrum.
Abstract: LaFeO3 nanospheres were synthesized by hydrothermal method followed by calcination. Citric acid was found to be key factor to the purity and the surface morphology of the LaFeO3 nanospheres. The obtained nanospheres have been structurally characterized by XRD which confirms the single crystalline orthorhombic structure. The structural information of the nanosphere was also confirmed from the Raman spectrum. HRSEM and AFM revealed that the prepared sample has been composed of spherical like morphology with an average size of about 45 nm. From XPS analysis, the chemical state of the LaFeO3 nanospheres was confirmed. Magnetic measurement indicates the products shows weak magnetic behaviour. The UV–Vis spectroscopy analysis shows strong absorption at 466 nm which confirms that the obtained material has excellent visible light absorption ability. Furthermore, the photocatalytic experiment demonstrates that the prepared LaFeO3 nanospheres exhibit well and stable photocatalytic activity for decomposition of methyl orange under visible-light irradiation.
TL;DR: In this article, La-modified solid solutions of BiFeO3 and BaTiO3 in different molar ratios have been synthesized using a solid-state reaction route, and structural and electrical properties of single phase (with minor secondary phase) of BFO-BT system have been studied in details to understand their ferroelectric and other properties.
Abstract: In the present investigation, La-modified solid solutions of BiFeO3 (BFO) and BaTiO3 (BT) in different molar ratios [i.e., (Bi0.5−x
La
x
Ba0.5)(Fe0.5Ti0.5)O3, with x = 0.0, 0.05, 0.10 and 0.15)] have been synthesized using a solid-state reaction route. Structural and electrical properties of single phase (with minor secondary phase) of BFO–BT system have been studied in details to understand their ferroelectric and other properties. Preliminary X-ray diffraction analysis confirms the formation of a new system, which is different from that of its parent compounds. Substitution of a small amount BaTiO3 into BiFeO3 enhances dielectric and ferroelectric responses and reduces electrical leakage or tangent loss. The ac conductivity obeys Jonscher’s universal power law. The electrical behavior of the samples was investigated by impedance spectroscopy in a wide temperature range (25–525 °C) at different frequency (1 kHz–1 MHz). The impedance spectroscopy of the materials also confirms the origin of the relaxation mechanism in the system.
TL;DR: In this article, the effect of deposition time on optical, structural and morphological properties of lead sulfide thin films were investigated by using UV-Vis-NIR absorption spectroscopy, X-ray diffraction (XRD), photoluminescence, field emission scanning electron microscopy (FESEM), high-resolution-transmission electron microscope (HRTEM), energy dispersive Xray Spectroscopy (EDS), and X-Ray photoelectron spectroscopic (XPS).
Abstract: In the present investigation, we have successfully synthesized lead sulfide (PbS) thin films by using simple, cost effective and facile aqueous chemical route. The effect of deposition time on optical, structural and morphological properties of PbS thin films were investigated by using UV–Vis–NIR absorption spectroscopy, X-ray diffraction (XRD), photoluminescence, field emission scanning electron microscopy (FESEM), high-resolution-transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The optical band gap energy was varied in the range of 0.96–1.56 eV. The XRD patterns revealed the formation of pure cubic crystal structure. FESEM micrographs demonstrated the conversion of morphology from pyramidal to interconnected nanocubic. HRTEM and selected area electron diffraction (SAED) pattern illustrated that nanoparticles are compact, well interconnected and single crystalline in nature. EDS spectrum confirms that deposited PbS thin films are in good stoichiometry.
TL;DR: In this paper, the size of the nanoparticles decreases with Zn doping down to 4nm, and the decrease of particle size is accompanied by a decrease of the band gap value from 3.34 eV to 3.28 eV.
Abstract: Nanometric size Zn-doped SnO2 particles with Zn concentration varying from 1 to 6 % were prepared using the co-precipitation method. X-ray diffraction patterns show for all samples a typical rutile-type tetragonal structure of SnO2 without any additional peaks from spurious phases. These results together with transmission electron microscopy analyses have shown that the size of the nanoparticles decreases with Zn doping down to 4 nm. According to UV–visible absorption measurements this decrease of particle size is accompanied by a decrease of the band gap value from 3.34 eV for SnO2 down to 3.28 eV for 6 % Zn doping. The electrical conductivity of the system has been investigated between 473 and 718 K, in the 200 Hz–5 MHz frequency range, by means of impedance spectroscopy. The temperature dependence of the bulk conductivity was found to obey the Arrhenius law with activation energies of 0.74 eV for SnO2 and 0.69 eV for 6 % Zn doping.
TL;DR: Indium doped tin oxide (SnO2:In) thin films were deposited on glass substrates by sol-gel dip coating technique as mentioned in this paper, which showed an inhibition of grain growth with increase in indium concentration.
Abstract: Indium doped tin oxide (SnO2:In) thin films were deposited on glass substrates by sol–gel dip coating technique. X-ray diffraction pattern of SnO2:In thin films annealed at 500 °C showed tetragonal phase with preferred orientation in T (110) plane. The grain size of tin oxide (SnO2) in SnO2:In thin films are found to be 6 nm which makes them suitable for gas sensing applications. AFM studies showed an inhibition of grain growth with increase in indium concentration. The rms roughness value of SnO2:In thin films are found to 1 % of film thickness which makes them suitable for optoelectronic applications. The film surface revealed a kurtosis values below 3 indicating relatively flat surface which make them favorable for the production of high-quality transparent conducting electrodes for organic light-emitting diodes and flexible displays. X-ray photoelectron spectroscopy gives Sn 3d, In 3d and O 1s spectra on SnO2:In thin film which revealed the presence of oxygen vacancies in the SnO2:In thin film. These SnO2:In films acquire n-type conductivity for 0–3 mol% indium doping concentration and p type for 5 and 7 mol% indium doping concentration in SnO2 films. An average transmittance of >80 % (in ultra-violet–Vis region) was observed for all the SnO2:In films he In doped SnO2 thin films demonstrated the tailoring of band gap values. Photoluminescence spectra of the films exhibited an increase in the emission intensity with increase in indium doping concentration which may be due structural defects or luminescent centers, such as nanocrystals and defects in the SnO2.
TL;DR: In this paper, the microwave absorbing properties of the Ni wax-composite were evaluated based on the complex permittivity (er ǫ −e′−−−je″) and permeability.
Abstract: Flower-like Ni structures composed of leaf-like flakes were synthesized through a facile solvothermal approach independent of surfactants or magnetic force. The evolution of the morphology was closely related to the variation of NaOH and volume ratios of ethylene glycol to water. The microwave absorbing properties of the flower-like Ni wax-composite were evaluated based on the complex permittivity (er = e′ − je″) and permeability (µr = µ′ − jµ″). The Ni wax-composite exhibited excellent microwave absorption performances with a minimum reflection loss of −46.1 dB at 13.3 GHz, corresponding to a matching thickness of 2.0 mm. In particular, the absorption bandwidth of RL below −10 dB was 3.6 GHz (11.7–15.3 GHz). The attenuation of microwave could be attributed to the dielectric loss and unique flower-like structure.
TL;DR: In this paper, the surface topography of Pt Schottky contacts on quaternary n-Al 0.08In0.08Ga0.84N thin film was analyzed using atomic force microscopy (AFM) and fractal analysis.
Abstract: The purpose of this study was to analyze surface topography of Pt Schottky contacts on quaternary n-Al0.08In0.08Ga0.84N thin film. To understand how the effect of temperature changes the layers surface, the surface topography was characterized through atomic force microscopy (AFM) and fractal analysis. Pt Schottky contacts grown on nanostructure Al0.08In0.08Ga0.84N thin film grown by molecular beam epitaxy technique on sapphire substrate at annealing temperatures range of 300–500 °C were used. AFM analysis was performed in contact mode, on square areas of 10 × 10 μm2, by using a Nanosurf Easyscan 2 AFM system. Detailed surface characterization of the surface topography was obtained using statistical parameters of 3D surface roughness, according with ISO 25178-2: 2012, provided by the AFM software. The results revealed that the high quality Schottky contact with the Schottky barrier heights and ideality factor of 0.76 and 1.03 respectively can be obtained under 30 min annealing at 400 °C in N2 ambience. The surface roughness of Pt Schottky contacts on quaternary n-Al0.08In0.08Ga0.84N thin film revealed a fractal structure at nanometer scale. Results obtained by fractal analysis confirm the relationship between the value of the fractal dimension and the statistical surface roughness parameters. AFM and fractal analysis are accurate tools that may assist manufacturers in developing Pt Schottky contacts on quaternary n-Al0.08In0.08Ga0.84N thin film with optimal surface characteristics and provides different yet complementary information to that offered by traditional surface statistical parameters.
TL;DR: In this paper, an analysis of the solidification process of pure Sn, binary Sn, Ag, Cu, Bi, Sn-Zn, and ternary Sn-Ag-Cu eutectic alloys was carried out using computer aided cooling curve analysis and differential scanning calorimetry.
Abstract: During last few decades, emerging environmental regulations worldwide, more notably in Europe and Japan, have targeted the elimination of Pb usage in electronic assemblies due to the inherent toxicity of this element. This situation drives to the replacement of the Sn–Pb solder alloy of eutectic composition commonly used as joining material to suitable lead-free solders for microelectronic assembly. Sn-based alloys containing Ag, Cu, Bi, and Zn are potential lead-free solders, usually close to the binary or ternary eutectic composition. For this reason a great effort was directed to establish reliable thermophysical data fundamental to interpret the solidification process and fluidity of alloys belonging to these systems. In this work, an analysis of the solidification process of pure Sn, binary Sn–Ag, Sn–Cu, Sn–Bi, Sn–Zn, Sn–Pb and ternary Sn–Ag–Cu eutectic alloys was carried out using computer aided-cooling curve analysis and differential scanning calorimetry.
TL;DR: In this article, the authors reported the fabrication of different TiO2 nanotube arrays (TiO2 NTs) by anodization method, which showed a remarkable efficiency of 1.56% when used in dye-sensitized solar cells.
Abstract: In the present work we reported the fabrication of different TiO2 nanotube arrays (TiO2 NTs) by anodization method. When used in dye-sensitized solar cells, the TiO2 NTs prepared in the two-step anodization process (2-step TiO2 NTs) showed better efficiency than those of TiO2 NTs prepared in one step anodization process (1-step TiO2 NTs). The 2-step TiO2 NTs show a remarkable efficiency of 1.56 %. This is higher than those of TiO2 NTs prepared in one step anodization process. Electrochemical impedance spectroscopy has been performed for qualitative analysis of charge transport process in dye-sensitized solar cells.
TL;DR: In this article, a double-dip method was used to obtain polycrystalline nature with monoclinic structure of CuO thin films. But the structural studies revealed that the deposited films exhibited poly crystal structure with a high absorbance in the visible range.
Abstract: Cupric oxide (CuO) thin films are deposited on glass substrates by double dip method at various molar concentrations of copper sulphate salt. Growth mechanism is derived using oxolation process. The structural studies revealed the deposited films exhibited polycrystalline nature with monoclinic structure. The change in the molar concentration of copper sulphate salt has pronounced effect on the microstructural properties of deposited thin films. XPS and EDS spectra confirm the presence of Cu and O. Micro Raman spectra shows two Ag and Bg active Raman mode peaks corresponding to CuO phase. Deposited films showed a high absorbance in the visible range with the bandgap value of 1.3 eV making it a suitable material as semiconductor tandem absorber for solar cells. Optical constants such as refractive index (n), extinction coefficient (k), optical conductivity (σ) and dielectric constants (e) were evaluated using an approximation protocol developed from well recognized procedures using the data obtained from UV spectroscopic technique. The prepared CuO thin films are identified as suitable candidates for optoelectronic devices and solar cell fabrication.
TL;DR: In this paper, the influence of synthesis conditions on the crystal structure, morphology, optical and magnetic properties was systematically studied using X-ray diffraction, scanning electron microscope (SEM), UV-Vis-NIR scanning spectrophotometer and vibrating sample magnetometer.
Abstract: P-type transparent conducting oxides copper delafossite CuFeO2 powders have been successfully synthesized by using hydrothermal method. The influence of synthesis conditions on the crystal structure, morphology, optical and magnetic properties was systematically studied using X-ray diffraction, scanning electron microscope (SEM), UV–Vis–NIR scanning spectrophotometer and vibrating sample magnetometer. The results indicated the precipitated precursor at pH value of 12 using 1 M NaOH as a base in the presence of hydrazine hydrate as a reducing agent hydrothermally treated at 280 °C for 96 h was transformed to pure rhombohedral 3R delafossite phase. SEM observations of these powders confirmed their hexagonal like structure. The transmittance of the sample was around 65 %. The optical band gap of delafossite–CuFeO2 sample prepared was 3.5 eV as a visible transparent material. Furthermore, magnetic properties behavior was identified and paramagnetism property was found at a room temperature. The saturation magnetization and coercive force for the pure sample were 1.2 emu/g and 58.35 Oe, respectively.