Crystalline Structure Properties Research Articles

Catalytic and photocatalytic activity of Urtica dioica-mediated Ud-ZnO nanoparticles

Due to their pollution-free process, low-cost, and high-quality products, plant-mediated synthesis routes have been increasingly integrated and extended for preparing a different kind of nanomaterials particularly metals/metal oxides nanoparticles (NPs). In this work, Urtica dioica (U. dioica) ethanolic leaf extract mediated ZnO NPs (Ud-ZnO NPs) were synthesized and applied for photodegradation of methyl orange (MO, C14H14N3NaO3S) and rhodamine B (RhB, C28H31ClN2O3) dyes under ultraviolet (UV) light irradiation. Also, the catalytic activity of the prepared Ud-ZnO NPs was examined for catalytic reduction of toxic 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The chemical structure, surface morphology, crystalline structure, elemental composition, and light properties of the prepared Ud-ZnO NPs investigated using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and UV–visible diffuse reflectance spectroscopy (DRS) analyses, respectively. The SEM analysis illustrated the hexagonal phase structure with no significant agglomerations. The particle size of synthesized Ud-ZnO NPs was ranging between 26.5 and 73.7 nm with a mean particle size of 44.9 nm. The optical band gap (Eg) of the synthesized Ud-ZnO NPs estimated via DRS spectroscopy using Tauc plot was found to be 3.14 eV. The quantitative photocatalytic activity of prepared Ud-ZnO NPs indicated that 73.4 % of MO and 85 % of RhB were degraded photochemically within 90 and 140 min, respectively, indicating high photocatalytic activity. The kinetics of the photodegradation MO and RhB reactions, and also, rapid catalytic reduction 4NP reaction was analyzed based on the Langmuir-Hinshelwood (L-H) model, indicating a pseudo-first-order reaction with the reaction rate constants of 0.0155 min−1, 0.0121 min−1, and 0.0158 s−1, respectively. The results verified the effectiveness of the U. dioica leaf extract as an active reducing and capping agent for preparing Ud-ZnO NPs.

The multi-scale structure and physicochemical properties of mung bean starch modified by ultrasound combined with plasma treatment

Plasma is a simple, effective and promising food processing technology with great potential for starch modification. Mung bean starch was subjected to ultrasound (300 W, 10, 30 and 50 min), plasma (40 V, 1, 3 and 9 min) and the synergistic treatment, as well as investigating its effects on the morphology, chain length distribution, molecular weight, crystalline structure and physicochemical properties of starch. Ultrasound and plasma treatment did not change the granule shape, but caused some corrosions on the surface, and dual treatment increased the damage degree of starch granules surface. All treatments decreased the molecular weight (Mw), amylopectin long chains and crystallinity but increased the gelatinization temperatures and enthalpy. Different from ultrasound irradiation, single plasma treatment significantly reduced the swelling power and pasting viscosities. Furthermore, dual treatment increased the thermal stability of starch paste, owing to the reinforcement effect between ultrasound and plasma. Thus, dual modification displayed an excellent ability to modify starch with specific characteristics and expand the potential application of mung bean starch in the food industry.

Salt-free synthesis of Cu-BTC metal-organic framework exhibiting mesoporosity and enhanced carbon dioxide adsorption

Cu-BTC (HKUST-1) metal-organic framework (MOF) in crystalline powder form was prepared by using a copper mesh as the metal source without involving any additional metal precursor, and its performance was evaluated for CO 2 capture. The crystalline structure, morphology, textural characteristics and surface chemical properties of the synthesized HKUST-1 samples were examined by XRD, SEM, N 2 physisorption, and FTIR. The MOF synthesized using the salt-free method exhibited high crystallinity, small size (~2 μm) and uniform crystal morphology, and mesoporosity. The CO 2 adsorption on the MOF was assessed at various temperatures and evaluated with respect to capacity, selectivity, kinetics, and heat of adsorption. Compared to HKUST-1 synthesized by the conventional method, the mesh-derived MOF exhibited a higher CO 2 adsorption capacity (48% higher at 1 bar and 25 °C), increase in CO 2 /N 2 adsorptive selectivity (~11%), as well as faster adsorption kinetics (by 73%). The heat of adsorption was found to increase as well particularly at higher coverages. The obtained CO 2 uptake (~5.2 mmol/g at 1 bar and 25 °C) is among the highest reported for this MOF. The synthesis procedure presented here encompasses high yield (up to 85%), while it requires fewer chemicals and generates less waste compared to the solvothermal approach. As such, it holds the potential to facilitate scaled-up production in a cost-effective and greener way, as the demand for highly efficient porous materials for gas adsorption applications, including CO 2 capture and H 2 storage, is anticipated to significantly increase in the near future. • A novel method for producing MOF powder crystals without using metal salts is reported. • Cu-BTC (HKUST-1) MOF was produced using copper mesh as the Cu source. • Crystal film is grown on the mesh and then dispatched into solution. • The salt-free derived HKUST-1 exhibited enhanced Cu active sites and bimodal porosity in the mesoporous range. • The mesh-derived MOF exhibited significantly enhanced CO 2 adsorption performance.

Influence of nitrogen ratios on rutile to anatase phase transition of titanium oxynitride thin films deposited via reactive magnetron sputtering

Thin films of titanium oxynitride deposited via reactive direct current (DC) magnetron sputtering method followed by annealing treatment at 500 °C for crystallization improvement. The thin films were grown under the Ar/O2/N2 gases mixture by various nitrogen ratios. The crystalline structure, surface morphology, and optical properties of the obtained thin films were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and ultraviolet-visible spectrophotometer, respectively. The rutile to anatase phase transition could be detected that increased with increasing the nitrogen ratio and also affected the crystallite size and the thickness of the thin films. The optical bandgap evaluated by the Tauc plot is in the range of 2.78–3.17 eV.

Defect-induced modification of band structure by the insertion of Ce3+ and Ce4+ in SrTiO3: A high-performance sunlight-driven photocatalyst

Ce3+ and Ce4+ ions were successfully substituted in Sr2+ sites of SrTiO3 nanoparticles (NPs) synthesized by the Pechini type sol–gel process and post annealing at 750 °C. The resulting Ce-doped NPs, with average particle sizes up to 31.2 ± 0.5 nm, exhibited the cubic perovskite structure of SrTiO3. According to the analysis of crystalline structure, valence states, electronic structure, and optical properties, the surface defects induced by the Ce3+/Ce4+ pair had an important influence in improving the process of light absorption, charge transfer and surface chemisorption. Accordingly, the NPs with nominal composition Sr0.97Ce0.03TiO3 had the best balance between light absorption enhanced by surface defects and defect-induced carrier traps, exhibiting the highest photocatalytic activity with 95.10 % of methylene blue dye removal, after 120 min of simulated sunlight irradiation.

The Effect of the In-Situ Heat Treatment on the Martensitic Transformation and Specific Properties of the Fe-Mn-Si-Cr Shape Memory Alloys Processed by HSHPT Severe Plastic Deformation.

This work focuses on the temperature evolution of the martensitic phase ε (hexagonal close packed) induced by the severe plastic deformation via High Speed High Pressure Torsion method in Fe57Mn27Si11Cr5 (at %) alloy. The iron rich alloy crystalline structure, magnetic and transport properties were investigated on samples subjected to room temperature High Speed High Pressure Torsion incorporating 1.86 degree of deformation and also hot-compression. Thermo-resistivity as well as thermomagnetic measurements indicate an antiferromagnetic behavior with the Néel temperature (TN) around 244 K, directly related to the austenitic γ-phase. The sudden increase of the resistivity on cooling below the Néel temperature can be explained by an increased phonon-electron interaction. In-situ magnetic and electric transport measurements up to 900 K are equivalent to thermal treatments and lead to the appearance of the bcc-ferrite-like type phase, to the detriment of the ε(hcp) martensite and the γ (fcc) austenite phases.

Structural and optical properties, electrochemical impedance spectroscopy, and Mott–Schottky analysis of ZnFe2O4 nanoparticle-decorated V2O5 rectangular nanosheets for photoelectrochemical applications

Herein, efficient ZnFe2O4 nanoparticle (NP)-decorated V2O5 nanostructure photocatalysts were synthesized for photoelectrochemical applications, and their crystalline structure, morphology, and optical properties of the synthesized samples were analyzed. The ZnFe2O4 NP decoration over the V2O5 nanostructure surface significantly influenced the optical properties with the optical bandgap varying from 2.12 to 2.20 eV. The charge-transfer kinetics were investigated through electrochemical impedance spectroscopy. The ZnFe2O4 NP-decorated V2O5 nanostructures exhibited the lowest charge-transfer resistance of 4.69 kΩ and maximum photocurrent density of ~ 0.17 × 10−3 A cm−2 in the light state, which is six times higher than that of pure V2O5 nanostructures. Further, Mott–Schottky (M–S) analysis was performed at fixed frequencies, which significantly influenced the flat potentials and carrier densities owing to the ZnFe2O4 NP decoration.

Anatomy of a Natural Sunlight Driven CdS/CoTiO3/ZnO Ternary Photocatalyst for Efficient Optical Properties and Removal of Reactive Orange 30

ZnO as a promising photocatalyst has gained much attention for the removal of organic pollutants from water. However, the main drawbacks of the relatively low photocatalytic activity and high recombination rate of photoexcited electron-hole pairs restrict its potential applications. Promoting the spatial separation of photoexcited charge carriers is of paramount significance for photocatalysis because the difference in the band positions makes the potential gradient at the composite boundary. In this work, binary CdS/ZnO and CoTiO3/ZnO are first prepared by dispersion method and then decorated with ZnO particles to construct CdS/CoTiO3/ZnO ternary composites. For this reason, the CdS/CoTiO3/ZnO ternary composites was effectively designed and analyzed for the crystalline structure, light absorption, photoexcitation behavior and surface morphological properties by X-ray diffraction, diffuse reflectance UV/visible absorption spectroscopy, photoluminescence spectroscopy and scanning electron micrograph respectively. The photocatalytic activity was examined by degradation of the dye solution spectrophotometrically. The results of photocatalytic degradation indicated that the CdS/CoTiO3/ZnO ternary composites are much higher than those of bare CdS, CoTiO3, ZnO and any binary composites such as CoTiO3/ZnO and ZnO/CdS. The enhanced activity could be attributed to the drop electron transfer from CdS to ZnO to CoTiO3 through the interfacial potential gradient in the ternary hybrid conduction bands. The enhanced electron transfer of CdS/CoTiO3/ZnO ternary composites was also applicable to degrade other reactive dyes.

New Type of Food Processing Material: The Crystal Structure and Functional Properties of Waxy and Non-Waxy Proso Millet Resistant Starches.

Resistant starch (RS) is widely used in the food industry because of its ability to regulate and protect the small intestine, but their distinct effects on the structural and functional properties of waxy and non-waxy proso millet starches are not completely understood. The crystalline structure and physicochemical properties of waxy and non-waxy proso millets’ starch samples were analyzed after heat-moisture treatment (HMT). The analysis revealed significant differences between the RS of waxy and non-waxy proso millets. The crystal type of proso millets’ starch changed from type A to type B + V. The relative crystallinity of the RS of waxy proso millet was better than that of non-waxy proso millet. The gelatinization temperature and thermal stability of RS significantly increased, and the pasting temperature (PTM) of the RS of waxy proso millet was the highest. The water solubility and swelling power of the RS in proso millet decreased, and the viscoelasticity improved. The correlation between the short-range ordered structure of RS and ΔH, and gelatinization properties has a stronger correlation. This study provides practical information for improving the nutritional benefits of waxy and non-waxy proso millet in food applications.

Fabrication of Ag/Ag2O incorporated graphitic carbon nitride based ZnO nanocomposite for enhanced Z-scheme photocatalytic performance of various organic pollutants and bacterial disinfection

In this work, the development of a novel Ag/Ag2O combined g-C3N4/ZnO (g-C3N4/ZnO-Ag2O) ternary photocatalyst was successfully prepared by facile calcination and hydrothermal precipitation method. The crystalline phase structure, surface morphology, chemical compositions, and optical properties of the as-obtained g-C3N4/ZnO-Ag2O photocatalysts (PCs) samples were also characterized by XRD, FT-IR, FE-SEM with mapping, HR-TEM, XPS, UV-Vis DRS and PL spectra exclusively. The photocatalytic enhanced performance of as-obtained g-C3N4/ZnO-Ag2O heterostructured PCs was exploited to aqueous methylene blue (MB) dye and 4-chlorophenol than that of pristine g-C3N4 PCs within 120 mins under visible-light irradiation. The g-C3N4/ZnO-Ag2O composite exhibits a high photo-degradation rate constant and good recycling stability towards the MB dye photo-decomposition. The photocatalytic upgrading performance might be recognized to the synergistic effect at SPR interface of Ag/Ag2O NPs, which superior visible light fascination and separation/transfer of photo-excited charges over the g-C3N4/ZnO heterojunction interface. Besides, the possible Z-Scheme photo-degradation pathway and charge separation mechanism were discussed. Hence, the existing work could probably deliver a novel way to develop highly capable composite PCs for environmental wastewater remediation.

Effect of the Cu content on the corrosion of (TiZrNiNb)100-xCux high-entropy alloys in NaCl solution

This study shows the differences of the microstructure, microhardnesss, crystalline structure and electrochemical properties of a (TiZrNiNb)100-xCux (x = 10, 15, 20, 25, 30) alloy when two manufacturing processes are applied: the arc melting (ingots) and the melt spinning process (ribbons). The results indicate higher anti-corrosion properties for the ribbon samples due to a higher amorphous structure with low electric conductivity which exhibits an improvement in hardness. This amorphous structure does not demonstrate dendritic segregation nor do the ingot samples; therefore, there is no evidence of intermetallic phases identified by the X-Ray analysis. The 10 and 15 at.% Cu alloy exhibited the highest corrosion resistance, regardless of the manufacturing route.

Annealing induced phase transition and optical properties of Ga2O3 thin films synthesized by sputtering technique

Gallium oxide (Ga2O3) thin films were deposited on c-plane sapphire substrates at low temperature (RT) by magnetron sputtering method using Ga2O3 ceramic target and were post annealed at various temperatures ranging from 500 to 900℃. The effect of annealing temperature on the surface morphology, crystalline structure, chemical composition and optical properties of Ga2O3 thin films were investigated. A phase separation is observed at 800℃ and α-phase Ga2O3 thin films is obtained at low annealing temperature while β-Ga2O3 at high temperature. With annealing temperature increases, the optical bandgap decreases from 5.47 to 5.00 eV and the surface morphology become more and more smooth. A broad emission band centered at 550 nm is observed for all samples which can be attributed to the donor acceptor pair (DAP) recombination related to the oxygen vacancies.

Effect of Stretching on Crystalline Structure, Ferroelectric and Piezoelectric Properties of Solution-Cast Nylon-11 Films.

Compared to polyvinylidene fluoride (PVDF) and its copolymers, castor-oil-derived nylon-11 has been less explored over the past decades, despite its excellent piezoelectric properties at elevated temperatures. To utilize nylon-11 for future sensor or vibrational energy harvesting devices, it is important to control the formation of the electroactive δ′ crystal phase. In this work, nylon-11 films were first fabricated by solution-casting and were then uniaxially stretched at different stretching ratios (SR) and temperatures (Ts) to obtain a series of stretched films. The combination of two-dimensional wide-angle X-ray diffraction (2D-WAXD) and differential scanning calorimetry (DSC) techniques showed that the fraction of the δ′ crystal phase increased with the stretching ratio and acquired a maximum at a Ts of 80 °C. Further, it was found that the ferroelectric and piezoelectric properties of the fabricated nylon-11 films could be correlated well with their crystalline structure. Consequently, the stretched nylon-11 film stretched at an SR of 300% and a Ts of 80 °C showed maximum remanent polarization and a remarkable piezoelectric coefficient of 7.2 pC/N. A simple piezoelectric device with such a nylon-11 film was made into a simple piezoelectric device, which could generate an output voltage of 1.5 V and a current of 11 nA, respectively.

Effect of external electric field on crystalline structure and dielectric properties of Bi1.5MgNb1.5O7 thin films* *Project supported by the National Natural Science Foundation of China (Grant No. 51602037) and the Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices (Grant No. KFJJ201510).

Bismuth-based cubic pyrochlore materials have attractive dielectric properties, especially dielectric tunability. The Bi1.5MgNb1.5O7 ceramic samples were prepared by solid state reaction. The XRD results and SEM pictures prove the raw material are well mixed and co-fired and the BMN cubic pyrochlore is well crystallized, no second phase was found in the result. BMN thin film were fabricated by depositing BMN ceramic nanoparticles on the sapphire. The BMN thin film has a high dielectric tunability of 43% at a bias voltage of 1.5 MV/cm, with loss tangent lower than 0.009. A Raman study of BMN cubic pyrochlore reveals O′–A–O′ and O–A–O bending modes contribute to 80% of dielectric permittivity, obstructing these modes such as applying external electric field can have apparent influence on dielectric constant. Berry Phase calculation results shows that A2O′ tetrahedrons are more easy to distort under an external field. The A-site Mg have the highest displacement (0.765028 Å), followed by A-site Bi cations (0.346317 Å). Compared to zero-bias thin film, the biased one with A–O and A–O′ bonds being stretched and external coulomb force applied on cations and anions, the dielectric constant under bias field dramatically decreased.

Effect of Polyacrylonitrile Precursor Orientation on the Structures and Properties of Thermally Stabilized Carbon Fiber.

The thermal stabilization process of polyacrylonitrile (PAN) precursor fiber was the key step to prepare high-performance carbon fiber. During the thermal stabilization process, the aggregation structure and the reactivity of molecular chains have significant effects on the microstructures and mechanical properties of carbon fiber. In the present paper, the effects of the orientation structure of PAN precursor fiber on the thermal stabilization reaction and the mechanical properties of carbon fiber were experimentally studied. Using multi-dimensional structural and mechanical properties tests, such as XRD, DSC, 13C NMR and Instron machine testing, the crystalline and skeleton structure, exothermic behavior, and tensile properties of PAN precursor fiber with different orientations in the process of thermal stabilization were characterized to reveal the relationship between microstructure evolution and tensile properties. The results showed that the orientation structure of PAN precursor fiber had an obvious effect on the thermal stabilization process and the tensile stress–strain characteristic. When the heat treatment temperature was lower than 200 °C, the crystallinity and crystallite size of PAN fibers with higher orientation degrees increased significantly. After sufficient thermal stabilization, the original PAN precursor fiber with a higher orientation degree could form more aromatic lamellar structures and showed better regularity. Furthermore, the yield strength and initial modulus of the fibers with a higher orientation degree increased due to the formation of more aromatic rings. The maximum increase in the percentages of yield strength and tensile modulus of the PAN fibers were achieved when the heat-treated temperature was 200 °C, and the percentage values were 138.4% and 158.7% compared to the precursor without heat-treatment. In addition, the elongation at break of the fibers with a higher orientation degree was also relatively larger.

Synthesis and comparative study on the structural and optical properties of ZnO doped with Ni and Ag nanopowders fabricated by sol gel technique

In this work we have tried to prepare Ni and Ag doped ZnO nanopowders using the sol gel technique. The influence of Ni and Ag (1, 3 and 5 mol.%) on the crystalline structure and optical properties of ZnO was investigated. The samples were characterized by XRD, FTIR and UV–visible spectrophotometer. XRD patterns confirmed the wurtzite formation of doped and undoped ZnO nanopowders. The average crystallite sizes of the prepared samples found from XRD were 19 nm for undoped ZnO, from 17 to 22 nm for Ni-ZnO and from 19 to 26 nm for Ag-ZnO. The average crystallite size of Ag-ZnO increased with increasing Ag contents. Different optical properties of Ni-ZnO and Ag-ZnO nanopowders were observed for different Ni and Ag content. The band gaps of Ni-ZnO and Ag-ZnO nanopowders were lower than that of the undoped ZnO (3.1 eV). The band gaps of Ag-ZnO were lower than that of Ni-ZnO. The optical properties of ZnO were enhanced by Ni (mol.%) in the UV region and by Ag (3 and 5 mol.%) in the visible region.

Influence of Crystalline, Structural, and Electrochemical Properties of Iron Vanadate Nanostructures on Flutamide Detection

Iron vanadate (FeVO4) nanostructures were prepared using controlled hydrothermal synthesis from low temperature to high temperature (90 to 180 °C). The temperature-dependent synthesis pointed that FeVO4 nanorods can be achieved with less reaction time. The as-obtained samples were characterized in detail to analyze the hydrothermal temperature effects on structural, morphological, and electrochemical properties. From the morphological results, it is observed that there is a substantial change in particle shape and size with the increase in temperature. As an outcome, the specimen synthesized at 150 °C revealed a higher specific surface area (16.11 m2 g–1) than other temperature-varied samples. Similarly, the electrical and electrochemical performance characteristics of the proposed electrodes were comparably explored through electrochemical impedance spectroscopy (EIS) and cyclic voltammogram (CV) analyses. It is ascrtained that the electrochemical activity of the catalyst is greatly influenced by the hydrothermal temperature. Under optimized voltammetric experimental conditions, the flutamide (FLT) detection current revealed a wide linear relationship in the range of 0.06 to 777.46 μM with the lowest detection limit of 0.054 μM. Furthermore, the proposed electrode displayed an excellent anti-interference ability and high reproducibility together with acceptable performance in the detection of FLT in human blood serum. The outcomes from this study will provide a path to understanding the effects of hydrothermal temperature with shorter reaction time on the crystalline structure, surface morphology, and electrocatalytic properties of iron vanadate nanostructures that are significant for countless practical applications.

Structure, Optical and Electrical Properties of the High Doped ZnO Thin Films Deposited By RF Magnetron Sputtering of Powder Target in Methane Ambient

The ZnO thin films were deposited by RF-magnetron sputtering of ZnO powder target using pure argon, argon with hydrogen and argon with methane as reactive gas. Surface morphology and crystalline structure of the films were studied by SEM, XRD and XRR techniques. Chemical composition and optical properties were investigated by SIMS, Raman scattering spectroscopy (RSS), PL spectroscopy and spectral ellipsometry. Electrical measurements were performed on the ZnO films deposited on SiO2-Si and silicon wafers n- and p-type with Ni contacts by TLM, IV, CV characteristics, admittance spectroscopy, Van der Pauw and Hall methods. It was found that growth morphology, crystalline structure, optical and electrical properties of the films are strongly affected by adding methane to argon during the deposition process. Adding of methane resulted in a destruction of hexagonal phase texture and considerable increase a size of ZnO nanocrystallites (from 50 nm for argon to 200 nm for argon/methane working gas). SIMS measurements demonstrated that methane promoted hydrogen incorporation into the ZnO film that was more than an order of magnitude larger in comparison with adding molecular hydrogen in the gas mixture at the same concentration. Adding of methane resulted in a high energy shift of near band edge ultraviolet photoluminescence band, quenching of deep level emission in the visible spectral range and increase of optical band gap from 3.24 to 3.45 eV. The strongest effect of methane has been found for electrical resistivity that reduced by 3 orders of magnitude in comparison with films deposited in pure argon. Additionally, electrical conductance of the ZnO film deposited at high methane concentration does not depend on measurement temperature. Hall method with combination with Van der Pauw resistivity measurements shows: strong n-type doping of the film; donor concentration more than 1020 cm-3 slightly depending on methane concentration; maximum electron mobility about 7 cm2/V s. The direct comparison of resistivity and donor concentration of the films deposited using methane and molecular hydrogen as doping precursors has demonstrated that doping efficiency of methane is about an order of magnitude larger than that of molecular hydrogen under similar deposition conditions. On the other hand, methane addition in working gas resulted in an intensity decrease of the E2L (100 cm-1) and E2H (438 cm-1) lines in the RSS that can be associated with some disturbance of the ZnO structure. Additionally a peak at 71 cm-1 was observed in some films that can be related to the metallic Zn. The possible mechanisms of the ZnO film formation, nature of the doping and electron transport mechanisms will be discussed.

Effect of sputtering power on structure and properties of ZTO films

Transparent conductive tin-doped zinc oxide (ZTO) thin films were deposited on glass substrate by using radio frequency (RF) magnetron sputtering method. The effect of sputtering power on crystalline structure, morphology, optical and electrical properties of the ZTO film was systematically studied. XRD results showed that the as-deposited ZTO thin films had a hexagonal wurtzite structure, with (002) orientation. Combining with SEM images, it was found that the grain size was increased with increasing sputtering power. The AFM images revealed that low sputtering powers of<210 W should be used to have ZTO films with small roughness (Rq). The optimized sample exhibited an average transmittance of 93.4% in the wavelength range of 400–900 nm, while the band gap had a significant red shift relative to that of the intrinsic ZnO. Carrier concentration and mobility of the ZTO films were decreased, whereas the resistivity was increased, with increasing sputtering power. The sample sputtered at 120 W had the maximized figure of merit (ФTC) of 11.87 × 10−4 Ω−1·sq, with the variation trend to nearly mirror-symmetrical with that of surface roughness of the films.

Fabrication and characterization of InN-based metal-semiconductor-metal infrared photodetectors prepared using sol–gel spin coated technique

We report on the growth and characterization of undoped indium nitride (InN) thin films grown on a silicon substrate. The InN thin films were grown on aluminium nitride (AlN) template with gallium nitride (GaN) nucleation layer using a relatively simple and low-cost sol–gel spin coating method. The crystalline structure and optical properties of the deposited films were investigated. X-ray diffraction and Raman results revealed that InN thin films with wurtzite structure were successfully grown. For InN thin film grown on a substrate with the GaN nucleation layer, its strain and dislocation density are lower than that of the substrate with the AlN nucleation layer. From the ultra-violet-visible diffuse reflectance spectrum analysis, the energy bandgap of the InN thin films with the GaN layer was 1.70 eV. The potential application of the sol–gel spin-coated InN thin films was also explored. Metal–semiconductor–metal (MSM) infrared (IR) photodetectors were fabricated by depositing the platinum contacts using two interdigitated electrodes metal mask on the samples. The finding shows that the device demonstrates good sensitivity and repeatability towards IR excitation at a wavelength of 808 nm. The photodetector characteristics at dark and photocurrent conditions such as Schottky barrier height (SBH) and ideality factor are determined. Upon exposure to the IR source at 3V applied bias, InN/AlN/Si device configuration displays rapid rise time of 0.85 s and decay time of 0.78 s, while InN/GaN/AlNSi demonstrates slow rise time of 7.45 s and decay time of 13.75 s.