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This study used radio frequency sputtering at room temperature to prepare a zinc oxide (ZnO) thin film. After deposition, the thin film was placed in a high-temperature furnace to undergo thermal annealing at different temperatures (300, 400, 500, and 600°C) and for different dwelling times (15, 30, 45, and 60 min). The objective was to explore the...
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Zinc oxide (ZnO) thin films were grown on silicon (100) substrate using radio frequency (RF) sputtering under various processing parameters including deposition time and annealing temperature. A series of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and scanning aco...
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... The increased thermal annealing dramatically increases the preferred C-axis orientation degree and continuously improves the ZnO crystallization structure [17]. In this work, thermal annealing temperatures are set to be higher than 300° because the poorer reaction process occurs for the excess Zn metal at 300 °C thermal annealing treatment due to higher melting point of Zn [17]. ...
... The increased thermal annealing dramatically increases the preferred C-axis orientation degree and continuously improves the ZnO crystallization structure [17]. In this work, thermal annealing temperatures are set to be higher than 300° because the poorer reaction process occurs for the excess Zn metal at 300 °C thermal annealing treatment due to higher melting point of Zn [17]. The growth of ZnO layer using pulsed laser deposition (PLD) and RF magnetron sputtering machine also require thermal annealing above 300 °C [18]. ...
The influence of high thermal annealing on the surface morphological, structural and optical properties of ZnO/AlN/GaN/AlN layers grown on Si substrate by MBE was investigated. The ZnO thin film was deposited on AlN/GaN/AlN heterostructures by radio frequency (RF) sputtering machine. Thermal annealing at different temperatures (600 °C and 800 °C) was applied to the sample in vacuum tube furnace with the existence of nitrogen flow. The surface morphological, structural and optical properties of samples were investigated by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), high-resolution X-ray diffraction (HR-XRD), and Raman spectroscopy, respectively. The ideal thermal annealing temperature is found to be 600 °C, which results in the films having the least amount of dislocation density, based on the findings of the optical and structural evaluation.
... RF sputter-deposited ZnO thin film on ITO glass annealed at a temperature range of 300 CÀ600 C with a step to 100 C is used to show the surface texture (Chin & Chao, 2013). In addition to the (002) and (101) crystalline phase peaks shown by the XRD pattern, the ZnO film annealed at 300 C also exhibits a Zn (101) diffraction peak. ...
... However, especially at lowtemperature, other intrinsic defects could not be ruled out, as will be discussed in this report. Despite a large number of reports on the effect of heat treatment on ZnO [6,7], in our understanding, there is still a gap in their knowledge, due to the difficulty in accessing it, mainly when the thermal annealing is performed in a high vacuum atmosphere, where very low pressure on the grain surface and very little oxygen concentration is presented. Bearing this in mind, the final parameters of the ZnO polycrystalline film will undoubtedly reflect on the physical properties of the films. ...
The control of native defects in the ZnO material is strongly important for a wide range of technological applications. In this paper, native defects are tuned via the post-thermal treatment of ZnO films in a high vacuum atmosphere. The microstructure of the as-grown ZnO film shows columnar growth and strongly polar-oriented grains along the c-plane (002). Also, the obtained results indicate that the as-grown film contains a high amount of intrinsic defects and strong lattice distortions. After the thermal annealing, the ZnO films display significant structural changes, which are reflected in their electrical, vibrational, and optical properties. Our findings suggest that these changes were attributed to the selective cleanup effect of the native defects and the partial deoxidation process mainly on the exposed particle surface (at high temperatures) tuned up by the thermal annealing temperature. According to DFT calculations, oxygen vacancies (VO) show lower energy, followed by zinc vacancies (Oi) and oxygen interstitials (VZn) indicating that VO defect is the most stable in ZnO. That sequence of stability could suggest the sequence of the annihilation of those defects, which is in line with our experimental findings.
... Regardless of the concentration of GDC films, the Raman peak shifted to lower frequencies with the increase in the annealing temperature. This behavior is a sizeinduced phenomenon observed in nanoscale systems, explained by the combined effects of lattice strain and associated with defect species and phonon confinement [64][65][66][67]. Kosacki et al. [66] and Weber et al. [67] stated that the width of the Raman peak has a linear dependence on the reciprocal of the crystal size. ...
... This behavior is a sizeinduced phenomenon observed in nanoscale systems, explained by the combined effects of lattice strain and associated with defect species and phonon confinement [64][65][66][67]. Kosacki et al. [66] and Weber et al. [67] stated that the width of the Raman peak has a linear dependence on the reciprocal of the crystal size. Similar behavior was reported by other authors [64][65][66][67]. ...
... Regardless of the concentration of GDC films, the Raman peak shifted to lower frequencies with the increase in the annealing temperature. This behavior is a size-induced phenomenon observed in nanoscale systems, explained by the combined effects of lattice strain and associated with defect species and phonon confinement [64][65][66][67]. Kosacki et al. [66] and Weber et al. [67] stated that the width of the Raman peak has a linear dependence on the reciprocal of the crystal size. ...
Gadolinium-doped ceria (GDC) nanopowders, prepared using the co-precipitation synthesis method, were applied as a starting material to form ceria-based thin films using the electron-beam technique. The scanning electron microscopy (SEM )analysis of the pressed ceramic pellets’ cross-sectional views showed a dense structure with no visible defects, pores, or cracks. The AC impedance spectroscopy showed an increase in the total ionic conductivity of the ceramic pellets with an increase in the concentration of Gd2O3 in GDC. The highest total ionic conductivity was obtained for Gd0.1Ce0.9O2-δ (σtotal is 11 × 10−3 S∙cm−1 at 600 °C), with activation energies of 0.85 and 0.67 eV in both the low- and high-temperature ranges, respectively. The results of the X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectrometer (ICP-OES) measurements revealed that the stoichiometry for the evaporated thin films differs, on average, by ~28% compared to the target material. The heat-treatment of the GDC thin films at 600 °C, 700 °C, 800 °C, and 900 °C for 1 h in the air had a minor effect on the surface roughness and the morphology. The results of Raman spectroscopy confirmed the improvement of the crystallinity for the corresponding thin films. The optimum heat-treating temperature for thin films does not exceed 800 °C.
... XRD spectra in Fig. 2(B) showed three diffraction peaks attributed to crystalline ZnO, corresponding to the crystal planes (100), (002), and (101) emerging at 2θ of 32.4, 34.8 • and 36.5 • respectively (Chin and Chao, 2013;Kumar et al., 2014). At higher deposition cycles such as 800 and 1000 cycles, the ZnO series show another crystalline diffraction peak from plane (110) at 2θ = 57.1 • , indicating the development of new plane of atoms in the lattice structure due to increased thickness of the coating and formation of larger crystal size, enhancing the crystallinity of the coatings. ...
The remediation of persistent organic pollutants in surface and ground water represents a major environmental challenge worldwide. Conventional physico-chemical techniques do not efficiently remove such persistent organic pollutants and new remediation techniques are therefore required. Photo-electro catalytic membranes represent an emerging solution that can combine photocatalytic and electrocatalytic degradation of contaminants along with molecular sieving. Herein, macro-porous photo-electro catalytic membranes were prepared using conductive and porous stainless steel metal membranes decorated with nano coatings of semiconductor photocatalytic metal oxides (TiO2 and ZnO) via atomic layer deposition, producing highly conformal and stable coatings. The metal - semiconductor junction between the stainless steel membranes and photocatalysts provides Schottky - like characteristics to the coated membranes. The PEC membranes showed induced hydrophilicity from the nano-coatings and enhanced electro-chemical properties due to the Schottky junction. A high electron transfer rate was also induced in the coated membranes as the photocurrent efficiency increased by 4 times. The photo-electrocatalytic efficiency of the TiO2 and ZnO coated membranes were demonstrated in batch and cross flow filtration reactors for the degradation of persistent organic pollutant solution, offering increased degradation kinetic factors by 2.9 and 2.3 compared to photocatalysis and electrocatalysis, respectively. The recombination of photo-induced electron and hole pairs is mitigated during the photo-electrocatalytic process, resulting in an enhanced catalytic performance. The strategy offers outstanding perspectives to design stimuli-responsive membrane materials able to sieve and degrade simultaneously toxic contaminants towards greater process integration and self-cleaning operations.
... The average sheet resistances of each of the samples are summarized in Table 1. While several prior studies have demonstrated that the resistivity depends on the annealing temperature [25], this study attempted to demonstrate that the resistivity induced by Ga-doping depends on the annealing atmosphere. The resistivity distribution graph clearly indicates that the lowest resistivity was obtained with ZnO:Ga-open air and ZnO:Ga-wet air layers. ...
... Consequently, the resistance value of the ZnO:Ga-N2 layer should be compared to that of the as-prepared ZnO. Therefore, as shown in Figure 4, only the ZnO:Ga-open air and While several prior studies have demonstrated that the resistivity depends on the annealing temperature [25], this study attempted to demonstrate that the resistivity induced by Ga-doping depends on the annealing atmosphere. The resistivity distribution graph clearly indicates that the lowest resistivity was obtained with ZnO:Ga-open air and ZnO:Gawet air layers. ...
Various annealing atmospheres were employed during our unique thermal-diffusion type Ga-doping process to investigate the surface, structural, optical, and electrical properties of Ga-doped zinc oxide (ZnO) nanoparticle (NP) layers. ZnO NPs were synthesized using an arc-discharge-mediated gas evaporation method, followed by Ga-doping under open-air, N2, O2, wet, and dry air atmospheric conditions at 800 °C to obtain the low resistive spray-coated NP layers. The I–V results revealed that the Ga-doped ZnO NP layer successfully reduced the sheet resistance in the open air (8.0 × 102 Ω/sq) and wet air atmosphere (8.8 × 102 Ω/sq) compared with un-doped ZnO (4.6 × 106 Ω/sq). Humidity plays a key role in the successful improvement of sheet resistance during Ga-doping. X-ray diffraction patterns demonstrated hexagonal wurtzite structures with increased crystallite sizes of 103 nm and 88 nm after doping in open air and wet air atmospheres, respectively. The red-shift of UV intensity indicates successful Ga-doping, and the atmospheric effects were confirmed through the analysis of the defect spectrum. Improved electrical conductivity was also confirmed using the thin-film-transistor-based structure. The current controllability by applying the gate electric-field was also confirmed, indicating the possibility of transistor channel application using the obtained ZnO NP layers.
... This process is acceptably cost-effective, has high deposition rate, simple and quick. The process to deposit can be done by altering several parameters such as current density [14][15][16], temperature [17], electrolyte concentration [18], deposition time [19], pH [20] and agitation [19,21]. The electrochemical deposition is mostly attempted for depositing conducting material onto conductor substrate. ...
... Yet, the EDX result of this study shows that the ratio between Zn to O for sample A, B and C was obtained at 2.81, 2.35 and 2.49 respectively. This ratio implies that there are numbers of Zn atom that are still free and did not bonding with O atom to fully form ZnO [15] . Figure 6, the V th values were determined as 2.21 V, 0.85 V and 1.22 V for sample A, B and C respectively. ...
This paper reported on the electrochemical deposition of zinc oxide (ZnO) on p-silicon (p-Si) (100) substrate in the mixture of 0.1 M of zinc chloride (ZnCl2) and potassium chloride (KCl) electrolyte at a volume ratio of 1:1, 3:1 and 5:1 namely Sample A, B and C. The deposition process was done in room temperature with a current density of 10 mA/cm2 for 30 minutes. Prior to the experiment, all samples were treated by RCA cleaning steps. All samples were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The results show that all samples have the same morphology of a flake-like structure with different Zn:O ratio that were 2.81, 2.35 and 2.49 for samples A, B and C. The current-voltage (I-V) characteristic graph was obtained by dark current measurement using Keithley SMU 2400 and the threshold voltage (Vth) values were determined at 2.21 V, 0.85 V and 1.22 V for sample A, B and C respectively which correspond with the Zn:O ratio where the highest value of Zn:O ratio can be found in sample A and the lowest in sample B. Based on these results, it shows that electrochemical deposition technique is capable of being used to deposit the flake-like structure ZnO on semiconductor material to form the p-n junction which behaves like a diode. The value of Vth seems to be depended on the ratio between Zn and O. Higher ratio of Zn and O will cause the higher value of intrinsic carrier concentration and built in potential which will increase the Vth value.
... SEM observations of the surface (Fig. 5a) and cross-section (Fig. 5b) showed that the film had a columnar structure with microscale pinholes (~10 µm) caused by sputtered metal clusters (~10 nm). This film morphology is consistent with that reported in previous studies involving RF magnetron sputtering [45,46]. ...
Fe-based nanocrystalline FeSiBPCuC alloys (NANOMET®) with a combination of high magnetic flux density, high permeability, and low iron loss have attracted much attention for use in magnetic core devices such as small power supplies, motors, and transformers. However, further improvement of the corrosion resistance is still required because surface oxidation during the water atomization process inevitably deteriorates the magnetic properties of these alloys. Here, we use a combinatorial magnetron sputtering system to fabricate new (FeSiBPCuC)100−x−yNix(Nb,Mo)y (0 ≤ x ≤ 10, 0 ≤ y ≤ 2 at%) amorphous thin films with enhanced corrosion resistance. We found that the co-presence of Ni (2–4 at%) and Mo (1–2 at%) in the FeSiBPCuC amorphous thin films promoted a further improvement of the corrosion resistance. The magnetic coercivity of (FeSiBPCuC)95.5Ni4.0Nb0.5 and (FeSiBPCuC)97.0Ni2.0Mo1.0 thin films was deteriorated compared with that of a FeSiBPCuC ribbon.
... The XRD diffraction pattern of the sputtered ZnO layer is illustrated in Fig. 2c. The pattern given in Fig. 2c clearly reveals [49,50]. Furthermore, the results uncover that not only the peaks of ZnO phase but also a peak of elemental zinc (Zn) with preferred orientation of (101) at 36.6° occur [49]. ...
In this study, P3HT:PCBM polymer-based solar cell devices with TiO2 and ZnO electron selective layers were separately investigated to compare effects of metal oxide layer in the inverted-type polymer solar cell structures. R.f. magnetron sputtering technique was used to fabricate highly oriented polycrystalline TiO2 and ZnO thin film layers onto FTO-coated glass substrates. The surface morphology, structural and optical properties of TiO2 and ZnO electron selective layers were studied by performing X-ray diffraction (XRD), confocal Raman spectroscopy, transmittance spectra and Atomic Force Microscope (AFM). Photovoltaic performance of inverted-type polymer solar cell based on Poly (3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) with different electron selective layers was executed to analyze the effects of TiO2 and ZnO thin film layers on the power conversion efficiency (PCE) value of inverted polymer solar cell (IPSC) devices. Produced devices with TiO2 and ZnO thin film indicated the best device performance with maximum PCE values of 2.88 and 3.49%, respectively.
... In addition, the stainless steel peaks at 33.5° and 35.5° and two of the characteristic peaks of ZnO at plane (002) and (101) which are at 35.5° and 36.5° [47,48] are likely overlapping due to their closed proximity. The XRD spectra however confirm the presence of polycrystalline Wurtzite hexagonal structure of ZnO and no evidence of the presence of other phases is found, confirming the proper crystallization process undertaken during the heat treatment. ...
... All the diffraction peaks of the ZnO thin films can be indexed to (100), (002), (101), (102), and (110). A Zn (101) peak is also observed in the thin films which may be attributed to insufficient oxidization [48]. ...
The performance of photocatalytic materials are largely dictated by the crystalline and optical properties of the semiconductors. The density of photo-generated electron and hole pairs is greatly influenced by the light penetration in photocatalytic material, leading to specific degradation kinetics. In this work, the relationship between the metal oxide film thickness and the overall materials optical and photocatalytic performances are systematically established for the first time. Thin films of semiconductor metal oxides such as TiO 2 and ZnO were prepared by atomic layer deposition (ALD) on stainless steel sputtered silicon wafers. The thickness of the metal oxide thin films was controlled by varying the number of deposition cycles (50-1000 cycles). The fabricated films were fully characterized to examine the change in morphology, roughness, crystallinity, optical and structural properties with varying thickness by several techniques such as Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), Diffuse Reflectance Spectroscopy (DRS) and X-Ray Photo-electro Spectroscopy (XPS).The films were generated to yield very consistent crystallinity, roughness and light absorption properties. Critical thicknesses were observed when a plateau in photocatalytic efficiency was reached at the thickness of 31 nm in the case of the TiO 2 and 89 nm thickness for ZnO films. The dependency of the thickness of nanometric ALD films on their photocatalytic efficiency results from the light diffusion and penetration within the material which was investigated through fundamentals and modelling of light-matter interaction in photocatalytic processes. This work establishes a new fundamental understanding of the operation and performance of photocatalysts for further development of advanced reactors and their scale-up.
