Metal Organic Decomposition Research Articles

Characterization of the VO<sub>2</sub> Thin Films Grown on Glass Substrates by MOD

This paper describes the deposition of Nb doped vanadium dioxide (VO2) films on a glass substrate by metal organic decomposition (MOD) and their thermochromic properties. The difference in thermochromic properties of VO2 thin films on a glass substrate was investigated with and without a buffer layer of Hf0.5Zr0.5O2 (HZO). The phase transition temperature of VO2 thin film successfully reduced from 83 to 43℃ on a glass substrate with a buffer layer of HZO. Without a buffer layer of HZO, the thermochromic properties of VO2 thin films deteriorated comparing with a buffer layer of HZO. HZO buffer layer effectively suppresses the miniaturization of VO2 crystallite size of thin film due to Nb doping. Moreover, it would block out the diffusion of Al, Na and Ca impurity ions from a glass substrate and the partial oxidation of VO2 thin films judging from XPS O1s spectra and XPS depth profile analysis. We conclude that the insertion of the HZO buffer layer is a useful technique for controlling the transition temperature of VO2 for the smart window applications by MOD.

Spin Hall magnetoresistance and the effect of post-annealing temperature in the MOD-grown HoIG

We present the fabrication of ultrathin Ho3Fe5O12 (HoIG) films on 111- oriented-Gd3Ga5O12 (GGG) via the metal-organic decomposition (MOD) method followed by a sequence annealing process. We characterized the crystal structure, surface morphology, and magnetic properties to study the effect of annealing temperature on the quality of MOD-grown HoIG films. For temperatures higher than 800 ⁰C, we observe the infiltration of Iron (Fe) from the HoIG film into the GGG substrate. In particular, the Fe-diffusion is significantly enhanced for a 1000 ⁰C-annealed sample of which crystal structure and magnetic properties are also affected. For temperatures lower than 800 ⁰C, on the other hand, the smooth surface and strong crystallinity cannot be guaranteed. This suggests that an annealing temperature of 800 ⁰C is the optimal condition for the MOD-grown HoIG film. The quality of the sample is further confirmed by measuring the spin Hall magnetoresistance (SMR) of HoIG/Pt, in which we found the unconventional angular dependence and comparable spin mixing conductance similar to the previous reports in other single crystalline IGs.

Room Temperature Electronic Functionalization of Thermally Sensitive Substrates by Inkjet Printing of a Reactive Silver‐Based MOD Ink

AbstractThe developments in inkjet printing technology and the printed electronics industry in the past two decades have provided cost‐effective, environment‐friendly, and reliable alternates to traditional methods of fabricating electrical devices. However, most commercial metallic inks require high sintering temperatures to form desired functional patterns, which limits the applications of printed electronics in scenarios that require electrical devices on thermally sensitive substrates, like biomaterials or bio‐synthetic composite materials. This study provides the synthetic route of a novel silver‐based metal organic decomposition (MOD) ink which is used to form highly conductive silver films on the thermally sensitive skin‐inspired silk/epoxy composite substrates by directly inkjet printing with accurate pattern control, whilst self‐decomposing and sintering at room temperature. The fabricated silver patterns on the thermally sensitive silk/epoxy composite substrate are highly conductive with conductivity of 4.65 × 104 S m−1. These silver patterns also show impressive malleability as bulk silver films, which can be further developed into motion sensors for wearable devices or medical applications. Our strategy provides a general platform for electronic functionalization without temperature constraints. The particle‐free, reactive silver‐precursor, and lower sintering temperature of the ink also widen the choices of substrates, as exemplified herein with outstanding printing quality and high electrical conductivity (1.20 × 106 S m−1) also achieve on paper.

The FMR line width and the structure in YIG films deposited by MOD on silicon (1 0 0)

In this work, yttrium-iron garnet (YIG) films deposited on silicon subtract were studied by ferromagnetic resonance (FMR). The samples were prepared by using the Metal-Organic Decomposition (MOD) method on two different thermal treatments (750 °C and 850 °C). The X-ray diffraction suggested the single phase of YIG while atomic force microscopy and scanning electron microscopy reveled film roughness, Rq < 0.2 nm. The FMR measurements showed very different linewidth of 139 Oe for the sample obtained at 750 °C and sample at 850 °C had a smaller linewidth of 93 Oe. The difference was mainly attributed to the different structural ordering of the two samples from the heat treatment at different temperatures.

NiFePB-modified ZnO/BiVO4 photoanode for PEC water oxidation.

Photoelectrochemical (PEC) water splitting has been recognized as the most promising approach for directly converting solar energy into chemical energy, and substantial efforts have been made to develop a highly efficient and low-cost photoanode for enhancement of PEC water splitting efficiency due to sluggish water oxidation reaction kinetics. A ternary NiFePB-modified ZnO/BiVO4 heterojunction photoanode was simply assembled by low-temperature hydrothermal, metal-organic decomposition and electrodeposition methods to improve the water splitting efficiency; its photocurrent density for water oxidation reached 1.66 mA cm-2 at 1.23 V (vs. RHE); in comparison, that of ZnO is only 0.4 mA cm-2. The onset potential manifests a cathodic shift of ∼283 mV compared to ZnO. The IPCE and the ABPE respectively are 3.1 and 6.4 times those of ZnO, respectively. This improvement is ascribed to the efficient separation of photogenerated electrons and holes by the formation of a heterojunction between ZnO and BiVO4 and the enhancement in the oxygen evolution reaction kinetics by the decoration of the co-catalyst NiFePB as a hole acceptor.

Facile synthesis of metal organic decomposition Al-doped ZnO ink for inkjet printing and fabrication of highly transparent conductive film

In this paper, a MOD (Metal organic decomposition) Al doped ZnO (AZO) ink was directly used for inkjet printing transparent and conductive AZO films. The ink was synthesized by using zinc acetate dihydrate and aluminum nitrate nonahydrate as precursor, 1,2-diaminopropane as a complexing agent, ethyl alcohol as solution, ethyl cellulose as addition agent. The thermal decomposition behavior of the MOD ink was investigated. The various MOD AZO inks were inkjet printed and heated at different temperatures for different times. The films were studied by X-ray diffraction, scanning electron microscopy, resistivity measurements and ultraviolet–visible spectroscopy. The results demonstrated that 0.2 M AZO (2 at%) film heated at 250 °C for 120 min showed highly preferential growth along the c-axis, uniform microstructure with a resistivity of 0.03 Ω cm and high transmittance more than 90% in the visible range of the spectrum with an optical band gap at 3.326 eV.

Laser-based, direct formation of thin copper–nickel alloy films with low thermal coefficient of resistivity

The growing market of printed electronics requires the development of new materials and processing technologies that enable the design of smart wearables, integrated sensors, and next-generation electronics. Against the backdrop of increasing material scarcity, these approaches must be resource-conserving and, at the same time, competitive with conventional technologies. As an alternative to nanoparticle-based inks currently used in printed electronics, another technology has been emerging in the last years that utilizes metal organic decomposition (MOD) inks, which are easy to fabricate and have a long shelf life. In this study, a method is presented that allows the direct formation of thin copper-nickel alloy films from a MOD ink. These alloys are preferably used for sensors like strain gauges as they exhibit a low thermal coefficient of resistivity (TCR). 250 nm thin alloy films are coated on glass substrates and thermally functionalized. In a conventional hot plate heat treatment under a nitrogen atmosphere, 10.2% bulk conductivity for a Cu55Ni45 alloy with a TCR of 8.3 × 10−5 K−1 is reached. X-ray diffraction analysis indicates the formation of a mixed crystal composed of nickel and copper atoms. A laser-based functionalization process is developed that allows the processing of Cu55Ni45 alloy films under ambient conditions without the formation of copper or nickel oxides. Laser-functionalized films exhibit 5.3% of the conductivity of bulk material. This study shows that metal alloy films can be fabricated directly from amine-based MOD inks.

Preparation and characterization of YMnO3 thin films by metal–organic decomposition

Hexagonal rare-earth manganese oxide YMnO3 thin films were prepared on yttria-stabilized zirconia (111) substrates by metal organic decomposition method. The crystallinity and morphology of YMnO3 thin films crystallized at various temperatures were examined by X-ray diffraction and atomic force microscopy measurements, respectively. Single phase YMnO3 was obtained for the sample prepared by annealing temperatures of 950 °C. AFM analysis revealed that a smooth surface with a roughness of 0.15 nm was achieved for YMnO3 thin film annealed at 950 °C and 1000 °C, while three-dimensional growth for other samples prepared at 750–900 °C, 1050 °C, and 1100 °C. A narrow band at 1.6 eV and a broad band at 5 eV due to electronic transitions in the manganese and oxygen bands were observed in an absorption spectrum.

Conformal Cu–CuNi Thermocouple Using Particle-Free Ink Materials

Flexible electronic sensors are today trending toward being smaller, lighter, and also conformal, while additive manufacturing capabilities are proving crucial in their rapid prototyping. Here, we report flexible and conformal thermocouples by printing liquid metal–organic decomposition materials, consisting of Cu and CuNi particle-free conductive inks. The printed Cu–CuNi (type T) thermocouple shows a linear temperature response with a sensitivity of 20.6 μV/°C and a response time below 2 s. In addition, the printed flexible thermocouple sensor exhibits high stability and reliability when subjected to external stimuli, such as bending, humidity, and thermal cycling. Printed conformal thermocouples using liquid metal decomposition ink materials provide a promising avenue toward miniaturized hybrid electronic devices.

Gamma-ray-induced migration of hydrogen isotopes in zirconium oxide coatings at room temperature

Hydrogen in materials is scientifically and technologically critical due to its unique behavior and large impact on material properties. Here, we report the migration of hydrogen isotopes in ceramic coatings induced by gamma-ray irradiation at room temperature. Nuclear reaction analysis performed simultaneously on hydrogen and deuterium reveals that residual hydrogen isotope impurities in zirconium oxide coatings fabricated by metal organic decomposition exist in the form of both stable and mobile species, whereas coatings made by magnetron sputtering contain only stable ones. The concentrations of mobile hydrogen and deuterium in the coating interior decrease significantly with the gamma-ray dose, whereas those of the stable species do not. An external hydrogen gas atmosphere prevents the depletion of mobile hydrogen and deuterium during the irradiation. This work opens a new strategy to transport and remove hydrogen isotopes from materials without elevated temperature.

Magneto-optical property and magnetic anisotropy of (100) oriented R0.5Bi2.5Fe5O12 (R = Eu, Sm, and Pr) thin films prepared by metal–organic decomposition

Bi-substituted rare-earth iron garnets, R3−xBixFe5O12 (Bi:RIG), where R represents one of the rare-earth elements, exhibit the excellent magneto-optical (MO) properties that increase with Bi content x. In addition, magnetic properties of Bi:RIGs, such as the magnetization, the magnetic anisotropy, and the magnetostriction, could be controlled by choosing rare-earth elements. In this paper, we report on R0.5Bi2.5Fe5O12 (Bi2.5:RIG, R = Pr, Sm, and Eu) thin films on Gd3Ga5O12 (GGG) (100) single crystal substrates prepared by the metal–organic decomposition method. XRD analysis reveals that Bi2.5:RIG thin films are grown along the same orientation with GGG substrates, and their lattice constants are dependent on the ionic radii of the rare-earth ions. MO measurements show that Faraday spectra of the Bi2.5:RIG thin films have a typical spectral structure observed for Bi:RIGs. The magnetic anisotropy constants, the uniaxial magnetic anisotropy energy Ku, and the magnetocrystalline anisotropy energy K1 of Bi2.5:RIG (R = Y, Pr, Nd, Sm, and Eu) thin films are investigated by using the ferromagnetic resonance measurement.

Thickness dependence of spin Seebeck resistivity in polycrystalline YIG films grown by metal organic decomposition method

In this work, we investigated the dependence of spin Seebeck effect (SSE) voltages on the thickness of yttrium iron garnet (Y3Fe5O12-YIG) thin films grown on a silicon (Si) substrate fabricated by a metal-organic decomposition (MOD) method. The thickness of films was controlled by repeated spin coating and annealing cycles. Based on grazing incidence X-ray diffraction measurements, the YIG thin films displayed high crystallinity without secondary peaks, despite the increase in thickness. Scanning electron microscopy revealed uniform, highly dense films for samples having a thickness in the range of 37–260 nm. Magnetic hysteresis loops showed similar coercivities of <36 Oe for all samples, confirming the high quality of the YIG films, regardless of mismatch between the lattice constants of YIG and the substrate. Spin Seebeck resistivity results revealed a strong dependence on the thickness of the samples and the local maxima for 138-nm-thick YIG. This was attributed to the effect of the magnon energy relaxation length (ξL), which is shorter in comparison to that of a single-crystal YIG film grown on gadolinium gallium garnet. In this study, facile fabrication of hundreds of nanometers-thick YIG films on a Si substrate was achieved, for applications involving thermoelectric energy harvesting.

Micron-scale crystallization of Bi:YIG by laser rapid thermal annealing at controlled atmosphere

Rapid thermal annealing (RTA) at 800–900 °C in air atmosphere is commonly used to crystallize bismuth-substituted yttrium iron garnet (Bi:YIG) deposited by vacuum evaporation techniques or metal–organic decomposition. However, the conventional RTA leads to undesirable effects in applications where Bi:YIG is the constituent material of a nano- or microstructure. Here we report on an approach to Bi:YIG local crystallization by a focused continuous wave laser beam (LRTA). The structural and optical properties of micron-sized Bi:YIG stripes crystallized in air, oxygen, nitrogen and argon atmospheres are discussed. The demonstrated LRTA can find practical applications for Bi:YIG monolithic integration on non-garnet substrates.

Optical and magneto-optical properties of bismuth-substituted neodymium iron gallium garnet films on glass substrates at the 1310-nm and 1550-nm wavelengths

We describe measured results of optical and magneto-optical (MO) properties of bismuth-substituted neodymium iron gallium garnet (Bi1Nd2Fe4Ga1O12, Bi1:NIGG) films prepared by spin coating on glass substrates and crystallized by metal–organic decomposition (MOD) method in the near-infrared (NIR) wavelengths of 1310 nm and 1550 nm. The optical constants of the Bi1:NIGG films were determined with a spectrophotometer measurement. The measured refractive index and absorption coefficient were about 1.835 and 55.8 cm−1, respectively, at the 1310 nm wavelength and about 1.837 and 29.8 cm−1 at the 1550 nm wavelength. The MO properties of the films were determined by measuring the Faraday rotation in the saturated magnetization region. The measured maximum Faraday rotation of the Bi1:NIGG film of about 1055-nm thickness was 0.032 °/μm and 0.016 °/μm at 1310-nm and 1550-nm wavelengths, respectively. The corresponding Figure-of-Merits (FoMs) were 5.64 deg/dB and 5.22 deg/dB at each wavelength. Our measured result indicates that the Bi1:NIGG films prepared by the MOD method are useful for integrated optical isolator and MO sensor applications because of relatively good optical transparency and MO characteristics.

Chemical CeO2-Based Buffer Layers for Fe(Se,Te) Films

Among other Fe-based superconductors, Fe(Se,Te) is particularly interesting because of the low structural anisotropy, large upper critical fields, low field dependence of the critical current density and low toxicity. It can also be grown as an epitaxial film on a metallic oriented substrate, making the fabrication of a Fe-based coated conductor (CC) possible. Less strict requirements on the template microstructure allow for the design of a simplified design compared to REBCO CCs. This design requires a buffer layer to promote the oriented growth of the superconducting film and avoid diffusion from the metallic template. In this work, CeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> based buffer layers are prepared on single crystals via two chemical deposition techniques, metal organic decomposition (MOD) and polymer assisted deposition (PAD). With the design of a suitable thermal treatment, it is possible to obtain oriented buffers with large flat grains and low values of surface roughness. Fe(Se,Te) films are deposited on these templates via laser deposition, and excellent samples are obtained when a Fe(Se,Te) seed layer is used to favour chemical matching with the buffer: sharp superconducting transitions around 16 K and critical current densities exceeding 1 MA cm <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">⁻</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 4.2 K in self-field are observed. These results are the demonstration of the feasibility of a Fe-based CC architecture, with all the relative advantages concerning process simplification and cost reduction.

Effects of Ta, Nb, Ba, and Sb concentration on structural, electrical, and optical properties of SnO2 thin films prepared by metal organic decomposition using spin coating

Ta-, Nb-, Ba-, and Sb-doped SnO2 thin films were prepared by the metal organic decomposition (MOD) method using spin coating. The effects of dopant concentration on the structural, electrical, and optical properties were investigated. The growth of polycrystalline films with the tetragonal rutile structure was confirmed by X-ray diffraction and atomic force microscopy measurements. The resistivity of Ta-, Nb- and Sb-doped SnO2 samples decreased to ∼10−3 Ωcm for dopant concentrations of around 1.5–3.0 at.%. The lowest resistivities were obtained for Ta- and Sb-doped SnO2 samples. On the other hand, no decrease in resistivity was observed for Ba-doped SnO2 samples. The band gap energy of Ta-, Nb-, Ba-, and Sb-doped SnO2 samples appeared to be larger than for those prepared by other methods. It was suggested that the structural deterioration may be related to the increase in the band gap energy for MOD prepared samples in addition to the Burstein-Moss effect.

Highly sensitive and stable H2 gas sensor based on p-PdO-n-WO3-heterostructure-homogeneously-dispersing thin film

The film-based gas sensor owning high compatibility with semiconductor device fabrication, plays an important role in the miniaturization and integration of the devices. Here, simple metal organic decomposition method and calcining procedure were used to prepare dense WO3 thin film with PdO nanoparticles being homogeneously dispersed. After painting the silver paste on its surface as electrodes, the H2 gas sensor was fabricated. At the optimal operating temperature of 160 °C, with response values (Ra/Rg) of 1.2 & 45.1 and response time of 38 s & 4 s, towards 500 ppb and 100 ppm H2, respectively, the sensor presents high sensitivity and low detection limit together. It is rare to report the H2 gas sensor based on dense semiconductor film with such low detection limit. Towards 500 ppb and 100 ppm H2, it still shows the same response values more than half a year later, which proves its stability. A good linear behaviour between the response and relative humidity is observed too. The chief cause of the better performance of the sensor may be the homogeneous and optimal distribution of the p-type PdO nanoparticles in n-type WO3 film, which is the character of this structure. In addition, the repeatability of the preparing process is very well too. All the better performances suggest that the H2 sensor based on this structure has a huge potential in practical application.

WITHDRAWN: Thickness dependence of spin Seebeck resistivity in polycrystalline YIG films grown by metal organic decomposition method

In this work, we investigated the dependence of spin Seebeck effect (SSE) voltages on the thickness of yttrium iron garnet (Y 3 Fe 5 O 12 -YIG) thin films grown on a silicon (Si) substrate fabricated by a metal-organic decomposition (MOD) method. The thickness of films was controlled by repeated spin coating and annealing cycles. Based on grazing incidence X-ray diffraction measurements, the YIG thin films displayed high crystallinity without secondary peaks, despite the increase in thickness. Scanning electron microscopy revealed uniform, highly dense films for samples having a thickness in the range of 37–260 nm. Magnetic hysteresis loops showed similar coercivities of <36 Oe for all samples, confirming the high quality of the YIG films, regardless of mismatch between the lattice constants of YIG and the substrate. Spin Seebeck resistivity results revealed a strong dependence on the thickness of the samples and the local maxima for 138-nm-thick YIG. This was attributed to the effect of the magnon energy relaxation length ( ( ξ L ) ), which is shorter in comparison to that of a single-crystal YIG film grown on gadolinium gallium garnet. In this study, facile fabrication of hundreds of nanometers-thick YIG films on a Si substrate was achieved, for applications involving thermoelectric energy harvesting. • Pure garnet-phase and high condensation YIG thin films were successfully grown on Silicon substrate via a facile fabrication method (i.e. MOD method). • The thickness of the sample was simply controlled by the repetition of coating and annealing processes. • A large spin Seebeck resistivity value of 37.3 nm/A which is comparable to YIG/GGG film was obtained. • The magnon energy relaxation length in poly-crystalline YIG/Si was obtained as 138 nm which is smaller than that of single-crystal YIG/GGG.

Deposition of Crystalline GdIG Samples Using Metal Organic Decomposition Method

Fabrication of high quality ferrimagnetic insulators is an essential step for ultrafast magnonics, which utilizes antiferromagnetic exchange of the ferrimagnetic materials. In this work, we deposit high-quality GdIG thin films on a (111)-oriented GGG substrate using the Metal Organic Decomposition (MOD) method, a simple and high throughput method for depositing thin film materials. We postannealed samples at various temperatures and examined the effect on structural properties such as crystallinity and surface morphology. We found a transition in the growth mode that radically changes the morphology of the film as a function of annealing temperature and obtained an optimal annealing temperature for a uniform thin film with high crystallinity. Optimized GdIG has a high potential for spin wave applications with a low damping parameter in the order of 10−3, which persists down to cryogenic temperatures.

Direct Laser Interference Ink Printing Using Copper Metal-Organic Decomposition Ink for Nanofabrication.

In this study, we developed an effective and rapid process for nanoscale ink printing, direct laser interference ink printing (DLIIP), which involves the photothermal reaction of a copper-based metal–organic decomposition ink. A periodically lined copper pattern with a width of 500 nm was printed on a 240 μm-wide line at a fabrication speed of 17 mm/s under an ambient environment and without any pre- or post-processing steps. This pattern had a resistivity of 3.5 μΩ∙cm, and it was found to exhibit a low oxidation state that was twice as high as that of bulk copper. These results demonstrate the feasibility of DLIIP for nanoscale copper printing with fine electrical characteristics.