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Alumina thin films were prepared by pulsed DC reactive magnetron sputtering using operating pressures that were varied from 3 to 20 mTorr. The films were immersed in DI water at temperatures of 55 °C and 65 °C for 30 min to study their hydrolysis corrosion behaviors. Unlike bulk crystalline Al2O3 materials, sputtered alumina films fabricated at operating pressures of 7 mTorr and higher were found to react with DI water within minutes, even under mild conditions. X-ray diffraction (XRD) and spectroscopic ellipsometry (SE) showed that the as-sputtered films had amorphous structures with various degrees of porosity within the films. The calculated porosity was found to increase from 17% to 25% as the operating pressure increased from 3 to 20 mTorr, respectively. Field-emission scanning electron microscopy (SEM) was employed to characterize the morphologies of the corroded films. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy showed the presence of hydroxide-containing functional groups on surfaces of alumina films, suggesting that the corrosion was due to a hydrolysis reaction. X-ray photoelectron spectroscopy (XPS) revealed distinct features in the non-corroded and corroded sample groups. For the corroded group (7–20 mTorr), the Al 2p peak showed two transitions, at 74.2 and 75.5 eV, attributed to Al–O and Al–OH, respectively. The O 1s peak intensities associated with the hydroxide content of samples in this group were found to be stronger than those associated with the lattice oxygen. The O 1s signal from adsorbed water at 533.7 eV became much stronger in corroded samples. The results also show that films fabricated at higher operating pressures yielded higher levels of pre-adsorbed hydroxide. Corrosion may progress through collective processes, including the formation of soluble aluminum hydroxide complex species and Al–O bond breaking during the proton transfer reactions between adsorbed water and hydroxide.

Well-separated inclined nanocolumnar TiZrN films were grown on silicon-wafer substrates by reactive magnetron co-sputtering with the oblique-angle-deposition (OAD) technique. The crystal structure, thickness, morphology and chemical composition of the prepared TiZrN films were investigated with the X-ray diffraction technique at the grazing-incidence angle (GIXRD), field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). The length, diameter and tilt angle of the nanocolumnar TiZrN films were evaluated. The microstructure and chemical composition were analyzed with transmission electron microscopy (TEM). The results indicated that the film crystallinity and physical morphology were influenced by the deposition time due to the self-annealing effect, which occurred during the nanocolumnar growth. Moreover, the hardness and surface wettability of the TiZrN films were studied using a nanoindentater and the water-contact-angle method, respectively. It was found that the hardness and hydrophobic surface of the TiZrN films decreased with the increasing deposition time.

In this work, the silver nanoparticle (Ag NP) films were deposited on glass slide by dc magnetron sputtering. The effect of annealing temperature on morphology and optical property were characterized by field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and UV–Vis-NIR spectroscopy, respectively. From the results, the size and inter-particle distance of Ag NPs depend on annealing temperature. The localized surface plasmon resonance (LSPR) band position shift to the blue with the annealing temperature increased. The surface enhanced fluorescence (SEF) effect of the Ag NPs films was investigated by emission spectra of Rhodamine 6G (Rh6G) fluorescent molecules. It was found that the florescent intensity of R6G, corresponding to the diameter and surface roughness of Au NP films. Finally, the Ag NPs film substrate offer a cost-effective with non-lithography fabrication potentially applied in plasmonic sensor chips for biomedical and food safety applications.

The hybrids nanostructure of gold nanoparticles (Au NPs) decorated on zinc oxide nanowires (ZnO NWs) was developed through sequential hydrothermal process and magnetron sputtering. The ZnO NWs grown on silicon wafer substrate via hydrothermal method at 90 °C using zinc acetate and hexamethylenetramine. Subsequently, the Au NPS were sputtering on to the ZnO NWs surfaces at 5-20 mTorr sputtering pressure. The morphology of the Au NPs grown on ZnO NW arrays was investigated by scanning electron microscopy and transmission electron microscopy. The results indicated that size and distribution of the Au NPs on ZnO NWs strongly depended on the sputtering pressure due to the mean free part and rate of gas phase collisions. The current work will be useful to develop high order hybrid nanostructure for nanosensor devices

Carbon nanotubes (CNTs) are considered as the most promising materials to solve the electromagnetic interference (EMI) issue. Various forms of CNTs including CNTs/polymer composites, metal nanoparticles-decorated CNTs and freestanding CNT buckypapers (CNT BPs) have been proposed to enhance shielding effectiveness. In this study, the synergistic effect of nickel nanoparticles (NPs) and relatively short CNTs for the enhancement of microwave shielding properties was investigated. CNT BPs were prepared by vacuum filtration of well-dispersed multi-walled CNTs and subsequently nickel was decorated on the CNT BPs (Ni/CNT) by pulsed DC sputtering technique with different deposition times of 0, 5, 10 and 15 min (hereinafter referred to as CNi0, CNi05, CNi10 and CNi15, respectively). The diameter of Ni/CNT increased from 8.74±0.53 to 72.5±3.2 nm and the conductivity improved from 9.57±0.87 to 12.57±0.59 S/cm when the nickel deposition time was 15 min. Nickel NPs were the mixed phases of nickel and nickel oxide with a dominant nickel phase. The shielding effectiveness at the frequency of 9.5 GHz achieved to -34.1 dB for CNi15. The enhancement of shielding effectiveness of CNi15 is attributed to the synergistic effect of CNTs and nickel NPs on wave dissipation

Crystalline hafnium nitride (HfN) thin films were successfully prepared by direct current (DC) reactive magnetron sputtering on a silicon substrate at room temperature. The effects of deposition time on physical structure, morphological, film composition, and optical property of the HfN thin film were systematically investigated by grazing incident X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet–visible-near infrared spectrophotometry, and color measurement. It was found that all prepared HfN thin films were cubic structure with (111) and (200). The FE-SEM images shown that the morphologies of the HfN films depict a dense and columnar structure which good adhesion with the silicon substrate. With the different deposition time, the HfN thin films exhibit different reflection, lightness, and color. It was found that the HfN thin films become high reflectance when the film thickness increases. In addition, the film color of all samples was yellow tones with the lightness of 55–65.

Ag-Sb-Te (AST) thin film was successfully fabricated on a flexible polyimide substrate by using DC magnetron sputtering from the AgSbTe (AST) target. As-deposited samples were annealed at temperatures between 300 and 450°C under vacuum for 30 min. Then, uni-leg AST thin film thermoelectric modules of five elements were fabricated. Thermal annealing induced a change of thermoelectric characteristic of the thin film from p-type material (300–350°C) to n-type material (400–450°C) through the change in structures (amorphous to crystalline, atomic composition ratio and surface roughness, etc.). The highest power factor was 0.97 mW m−1 K−2 and 0.065 mW m−1 K−2 for p-type and n-type, respectively. The maximum power generation of the uni-leg AST thin film thermoelectric module was approximately 0.88 nW for p-type and 0.54 nW for n-type, with a temperature difference of around 20 K.

The amorphous tantalum oxynitride (TaO x N y ) thin films were prepared on silicon (100) substrates by magnetron sputtering system with different techniques of conventional reactive sputtering and reactive gas-timing (RGT). The films were studied via spectroscopic ellipsometry (SE) measured in the range of 0.75–5.0 eV with 0.025 eV interval at 70° incident angle, and the optical model based on Tauc-Lorentz function was constructed to extract the properties of the films. The SE results indicated that all prepared films were grown homogeneously and show different optical properties upon their deposition conditions and techniques. The optical properties of film prepared by conventional reactive sputtering were close to the tantalum oxide film (TaO). The refractive index and optical band gap (E g ) of RGT samples changed with the oxygen timing and correlated with the change of oxygen and nitrogen concentration of the films. In addition, the morphologies, crystallinities, atomic concentrations and distributions of nitrogen atoms in the films analyzed by field-emission scanning electron microscopy, glazing-incident X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy are also discussed.

Nanocolumnar titanium zirconium nitride (TiZrN) films deposited on silicon wafer substrates were fabricated via reactive magnetron co-sputtering with oblique angle deposition (OAD) at room temperature. The influences of the sputtering power of Zr target varied from 100 to 300 W, on the structure, morphology and composition of the nanocolumnar TiZrN film were investigated by gracing-incidence X-ray diffraction (GIXRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscope (AFM) and photoelectron spectroscopy (PES). The GIXRD patterns revealed that the prepared films deposited at different sputtering powers of Zr target were crystalline in cubic phase with preferential orientation (111) and (222) planes of ZrN and TiN, respectively. The morphology obtained from FE-SEM showed well aligned slanted nanocolumnar structure, which come from the OAD technique. Increasing the sputtering power of Zr target, led to high adatom energy and enhanced collision effect during film deposition which the nanocolumnar showed obvious change in the diameter, length and tilt angle. The EDS mapping inside the nanocolumnar confirmed the homogeneity of the Ti, Zr and N element distributed in the nanocolumnar TiZrN films. Finally, the tribology behavior was preliminarily investigated based on the hardness of the nanocolumnar film and discussed in this manuscript.

Ar&H2 plasma treatment was proposed to enhance the response of a p-CuAlO2 sensor toward volatile organic compounds. Comprehensive defect characterization studies indicate a substantial increase of surface unsaturated oxygen vacancy (VO) defects via plasma treatment, which could provide active sites for molecule adsorption and the subsequent interfacial redox reaction.

Ag-added Ge2Sb2Te5 thin films were prepared by a pulsed-DC co-magnetron sputtering process using Ge2Sb2Te5 and Ag targets. The effect of variation in Ag content through variable power on Ag target was studied on the microstructural and thermoelectric properties of as-deposited and fast annealed thin films at 400 °C in a vacuum. It is found that Ag addition induces enhancement in conductivity. When the power on Ag target is exceeded to a critical power, Ag8GeTe6 phase formation occurs mixed with Ge2Sb2Te5 cubic structure which limits the thermoelectric performance. Best conditions provide the films having a lowest electrical resistivity as 0.98 × 10−4 Ω cm and the maximum power factor as 5.83 × 10−3 W m−1 K−2.

High-performance recyclable SERS substrates with well-ordered hybrid nanostructure gold nanoparticles (Au NPs) decorated on titanium dioxide nanorods (TiO2 NRs) were successfully prepared by combining two methods. The TiO2 NRs were fabricated by electron-beam evaporation with glancing-angle deposition (GLAD) technique, then the Au NPs were decorated onto the TiO2 NRs surfaces by deposition-precipitation (DP). The physical structures of the obtained hybrid nanostructures were characterized by field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscope (TEM), and grazing incident angle X-ray diffraction (GIXRD). The results indicated that size and density of Au NPs on TiO2 NRs were controlled by HAuCl4 concentration for optimization of the SERS performance whose the detection of MB molecules was achieved at an enhancement factor of 6.5 × 107 with 9.76%-RSD at 1626 cm−1. More significantly, the optimized hybrid nanostructure SERS substrates exhibit excellent recyclability. These hybrid nanostructure SERS substrates were therefore promising towards detection of TNT for homeland security applications, as well as an on-site SERS platform.

The preparation and characterization of nickel oxide (NiO) thin film for electrochromic smart window applications are studied. The NiO thin film was prepared by the DC magnetron sputtering from a pure nickel target. The sputtering power was varies in the interval 50–200 W. The crystallinity and physical morphology of NiO films are characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. The XRD result revealed that polycrystalline NiO thin films with preferred growth directions along (111) and (200) planes are obtained. Moreover, the electrochromic property of NiO thin films was investigated with a UV-Visible spectrophotometer. The colored state of the electrochromic cell was obtained by the ion insertion at the 1-V external applied bias in 0.1 M KOH. The reversibility between the colored and bleached states is confirmed by the optical transmittance. The result shows the optical contrast as high as 28.68., Дослiджено процес виготовлення i параметри тонких плiвок NiO для застосування в електрохромних смарт-вiкнах. Плiвки зробленi методом магнетронного напилення з постiйним струмом iз використанням мiшенi з чистого нiкелю. Потужнiсть напилення змiнювалась у межах 50–200 Вт. Кристалiчна структура та морфологiя плiвок NiO визначенi методами дифракцiї рентгенiвських променiв (ДРП) i сканувальної електронної мiкроскопiї (СЕМ), вiдповiдно. Результати ДРП показують кращий рiст полiкристалiчних плiвок в площинах (111) i (200). Крiм того, електрохромнi властивостi тонких плiвок NiO вивчались за допомогоюспектрофотометра ультрафiолетового та видимого дiапазону. Забарвлений стан електрохромної комiрки отримановведенням iонiв з концентрацiєю 0,1 M KOH при змiщеннi 1 В. Оборотнiсть переходiв мiж забарвленим i безбарвним станами пiдтверджено за допомогою коефiцiєнта пропускання. Знайдено, що величина оптичного контрасту досягає 28,68.

Nowadays, the simplicity of both designing and fabrication process of a terahertz (THz) resonator-based sensing technique leads to its ongoing development. The consumable THz resonator needs to be easily integrated into an existing terahertz time domain spectroscopy (THz TDS) measurement system. It should also be able to be fabricated in a mass scale with a low production cost. In this work, a metal-coated surface plasmon resonance- (SPR-) based sensor is simulated and designed as a low-cost refractive index sensor utilizing rigorous coupled wave analysis (RCWA). To demonstrate our methodology, we design a gold-coated grating with a polydimethylsiloxane (PDMS) as a substrate, in order to perform quantitative analysis of gasoline-toluene mixture composition, which has a refraction index variation of 0.1 at THz frequency. The grating period is tuned such that its surface plasmon resonance (SPR) frequency matches with the peak frequency of the THz TDS system. Moreover, other grating parameters, i.e., a filling factor and a grating depth, are optimized to increase the sensor sensitivity and sharpen the resonance dip. High sensitivity up to 500 GHz/RIU with a refractive index resolution up to 0.01 is numerically revealed. The H-field of the designed grating is then evaluated to indicate a strong SPR excitation. The well-developed designed grating introduces a promising, low-cost, and easily fabricated THz refractive index sensor.

Silver nanorod arrays deposited on a silicon wafer by employing the DC magnetron sputtering system have been investigated as reproducible and reusable SERS-active substrates. 2-Methylisoborneol (2-MIB) is used as a test molecule to exploit the uniformity, reproducibility and reusability of the fabricated substrates. SERS chips are found to be reusable by simple washing with DI water. Quantitative measurements show a good correlation between the intensity and molar concentration of 2-MIB. SERS chips can detect 2-MIB as low as 1 ppt, limit of detection. The present method is a single package of high SERS performance, large-scale production, ultrasensitive, uniform, reproducible and reusable.

Higher-order Guided Mode Resonance (GMR) in a symmetric two-dimensional embedded grating-waveguide structure is theoretically demonstrated in this paper through a phase matching mechanism of leaky modes along second-order diffraction planes. In addition to the fundamental-order, multiple resonances are introduced at normal incidence and they are polarization independent. A strong localization of the resonance modes exists in both orders. The device is proposed for multiple color surface enhanced fluorescence that is compatible to a conventional fluorescence reader. The enhancement scheme is by increasing light absorption via the excitation of a strong evanescent wave as an extension of a resonance mode. GMR device is designed to have resonances overlapping fluorophores’ absorption spectra. The concept is verified using numerical calculations, Rigorous Coupled Wave Analysis and Homogeneous Waveguide Approach. The device is fabricated and experimentally performed for fluorescence enhancement using a microarray of Cyanine 3-labeled goat antibody and Cyanine 5-labeled goat antibody. The fluorescence signal is characterized using a low-cost CMOS array. This implementation can be very useful in a multiplex detection, where the cost of the reader can be minimized.

Optimization of substrate heating during sputtering processes is essential to obtain desired microstructures of deposited thin films, as it provides the required energy flux during the nucleation and growth. In this work, Ge2Sb2Te5 thin films were prepared by a pulsed-DC magnetron sputtering process at optimized plasma conditions (pulsed frequency and pulse reversal time). The effect of substrate heating, in temperature range of 250–450 °C, was systematically investigated on the process throughput and various properties i.e. microstructure, morphology, atomic composition, carrier concentration, mobility and Seebeck coefficient of deposited films. The substrate heating was found to be required to obtain films in cubic crystalline phase. Through the optimization of substrate temperature, process throughput and surface properties, electrical properties as well as thermoelectric power factors were enhanced. The maximum power factor value of thin films was achieved as 0.77 mW m–1 K–2 for the substrate temperature as 400 °C.

This work reports the enhancement of NO2 gas sensing response which owing to the incorporation of Ag nanoparticles into WO3 nanofiber matrices. Ag-doped WO3 nanofibers were fabricated by electrospinning. The Ag dopant levels ranged from 1 to 10 mol%. The microstructures and chemical compositions were examined using a series of material characterization methods including TEM, SEM, XRD, and XPS. Porous mats of nanofibers comprising monoclinic WO3 nanoparticles (28–39 nm) incorporated with small Ag particles were observed. The NO2 gas sensing performance was investigated at various gas concentrations (0.5–5 ppm) and operating temperatures (200–275 °C). For 5 ppm NO2 gas detection measured at 225 °C, the 3 mol% Ag-doped WO3 nanofiber gas sensor exhibited the highest gas response (Rg/Ra) of 90.3. This was approximately 9 times higher than that of the undoped sample. The response and recovery time were found to be in the range of 6–18 min. The response analysis obtained from CH4, NH3, SO2, H2S, and NO2 gas measurements suggests that the sensor has excellent selectivity toward NO2 gas. The improved gas response of Ag-doped WO3 nanofibers was attributed to both electronic and chemical sensitization mechanisms provided by Ag nanoparticles. Significant decreases in gas responses were observed in the samples with higher Ag dopant levels (5 and 10 mol%), where the crystallite size of Ag nanoparticles became too large and hindered their catalytic effects.

In this research, the nanostructured patterns were fabricated by the CF 4 plasma etching process on the SiO 2 -based substrates, and treated with the Teflon coatings for superhydrophobicity and antireflection. First, the nickel thin films were deposited on the substrates by the PVD sputtering process at various deposition times. The prepared thin films underwent the rapid thermal annealing at 500 °C in order to promote the agglomeration of the nickel nanoparticulate patterns, which acted as the etch-resistant masks. These patterned substrates were consequently etched by the CF 4 plasma. After the etching process, the nickel masks were removed by the nitric acid rinse. Subsequently, the polytetrafluoroethylene films were coated on the nanostructured surface in order to achieve the superhydrophobic properties. The samples were characterized by the field-emission scanning electron microscopy (FESEM), UV-Vis-NIR spectroscopy, and the contact angle measurements to study the physical morphologies, optical transmission spectra, and wettability of water for each sample condition. The results showed that the roughness of the etched surface greatly affected the variations of the superhydrophobic properties, and the antireflective surfaces. The developed nanostructured patterns were highly potential for several applications in optoelectronic and solar energy materials.

In this work, the DC reactive magnetron sputtering were used to deposit the chromium nitride (CrN) thin films on silicon (100) wafers and 304-type stainless steels in argon-nitrogen gas mixture at room temperature. The effect of nitrogen partial pressure ratios [%PN2 = PN2/(PN2+PAr)×100] on the microstructural were studied. The crystal structure of the prepared CrN films were analyst by X-ray diffraction. For the physical morphological analysis, atomic force microscopy and field-emission scanning electron microscopy were used. An element analysis of the CrN thin films were performed by energy dispersive X-ray spectroscopy (EDS). It was found that the deposition rate of the films increased with decreasing the nitrogen partial pressure ratio. The changes in crystal structures and morphological related with nitrogen partial pressure ratio were systematically investigated and discussed in this paper.

Vertically aligned nitrogen-doped multi-walled carbon nanotubes (N-MWNTs) were synthesized by the chemical vapor deposition (CVD) at 900 °C using imidazole mixed with ferrocene as carbon and nitrogen sources, and catalyst, respectively. The effects of ammonia (NH3) and hydrogen (H2) flow rates on the growth of N-MWNTs were investigated (hereafter referred to A-N-MWNTs and H-N-MWNTs, respectively). Transmission electron microscopy (TEM) revealed the bamboo-like structure of the N-MWNTs, in which the separation between individual bamboo compartments decreased with increasing nitrogen concentration in N-MWNTs. X-ray photoelectron spectroscopy (XPS) analysis results supported that the nitrogen concentrations in N-MWNTs is 0.55 at.%, whereas A-N-MWNTs and H-N-MWNTs with the flow rate at 10 standard cubic centimeters per minute (sccm) (10A-N-MWNTs and 10H-N-MWNTs, respectively) showed 1.14 and 4.06 at.%, respectively. We found that the optimal conditions for the highest nitrogen-doped multi-walled carbon nanotubes (MWNTs) was a flow rate of NH3 and H2 at 10 sccm. Results from field emission measurements indicated that the turn-on fields of N-MWNTs, 10A-N-MWNTs and 10H-N-MWNTs were 6.7, 4.3 and 3.1 V/µm, respectively, while the field enhancement factors (β) were 5230, 10,805 and 20,390, respectively. Furthermore, the current density of N-MNWTs increased with increasing the nitrogen atoms in MWNTs. The results support that field emission based on N-MWNTs is a good emitter with low turn-on field and large field enhancement factor. Nitrogen doping in MWNTs makes them attractive candidates as high-performance field emitters.

Growth of silicon dioxide (SiO2) nanorods were fabricated via electron beam evaporation with oblique angle deposition technique approach at different film thickness. The morphologies, optical and wettability properties were characterized by field-emission scanning electron microscopy, spectrophotometry with angle dependence technique and contact angle measurement, respectively. Compared with that on the SiO2 thin films, the transmission on the SiO2 nanorods is significantly improved. The transmission is decreased with the height of the SiO2 nanorods. In addition, the result indicated that the SiO2 nanorods provide enhancement wettability which can function as the super-hydrophilicity surface. The experiment analysis of the thickness dependence omnidirectional anti-reflection and super-hydrophilic characteristics will benefit the design of self-cleaning glass application.

In this paper, the effect of oxygen flow rate on the physical microstructural, morphological and optical property of copper oxide (CuO) thin films have been reported. The CuO thin films were prepared by reactive magnetron sputtering without an external heating process. The film crystallization, morphological and surface roughness were characterized by the grazing-incident X-ray diffraction (GIXRD) and field-emission scanning electron microscope (FE-SEM) respectively. The optical transparent of the prepared samples were determined by UV-Vis-NIR spectrophotometer. The results shown that the deposition rate of the films was decreased with increasing in oxygen flow rate. The surface roughness was significantly affected by the change in oxygen flow rate. The results shown that the CuO thin films fabricated at 20 sccm-oxygen flow rate exhibited good crystal structure and transparent.

The tungsten oxide (WO 3 ) and bismuth vanadate (BiVO 4 ) thin films were successfully deposited on indium doped tin oxide (ITO) by dc reactive magnetron sputtering and spin coating technique, respectively. The physical structural were characterized by field-emission scanning electron microscopy (FE-SEM) and X-ray diffractometry (XRD). The photoelectrocatalytic water oxidation of ITO/WO 3 and ITO/WO 3 /BiVO 4 electrodes were compared under visible light irradiation. The double layer of WO 3 /BiVO 4 thin film are present the enhancing efficiency of water oxidation comparing with single WO 3 layer. The results showed the improvement of charge transfer by using heterojunction nanostructure semiconductor electrode in order to suppress the recombination effect and enhance an efficient of water splitting.

Copper oxide (CuO) thin films were prepared on glass slide and silicon wafer substrates using dc reactive magnetron sputtering at different operating pressure. The high purity Cu target was used, and sputtering was carried out in argon and oxygen atmosphere. The operating pressure was varied from 10 to 40 mTorr. The physical microstructure and optical properties were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and spectrophotometer. For the crystal structure, the XRD results indicated that the prepared CuO thin films were polycrystalline with monoclinic structure. The FE-SEM results demonstrated the increased of the dense pack structure for the films deposited at low operating pressure. The average optical transmittance at visible region of the film was about ∼50%.

Copper oxide thin films were prepared on silicon wafer and glass slide substrate by dc reactive magnetron sputtering using a copper target without substrate heating. As-deposited CuO thin films were then annealed at various the temperatures in air ambient. The effects of annealing treatment on the physical morphology, optical property of the prepared samples were studied by glancing incident X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM), UV-Vis-NIR spectrophotometer. The results shown that the crystallinity of the CuO thin films was significantly improved as an annealing temperature increased. Additionally, the sheet resistance measurements were characterized on as-deposited and annealed samples in order to discuss the electrical properties.

Aluminum-doped zinc-oxide (AZO) thin films were fabricated by pulsed dc magnetron sputtering with glancing-angle deposition (GLAD) techniques on silicon wafers and glass substrates. During the film deposition, the incident angle, α, between the particle flux and the substrate normal was carefully changed from 45° to 85°. The prepared samples were investigated for the film physical morphologies, crystallinity, optical transmission, and electrical properties based on the field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UV-VIS-NIR spectrophotometry, and Hall-effect measurements, respectively. The microstructures evolved from the columnar structures to the inhomogeneous film structures as the deposition angle was increased. When the deposition angle was increased, the deposition rate was gradually decreased. All the prepared films illustrated the hexagonal structure with the (002) and (103) orientations. The average transmission of the AZO thin films in the visible range was above 80%. In addition, the best deposition conditions of the AZO thin films could be applied to the transparent electrodes for the solar cell applications.

Local structures of nitrogen doped zinc oxide (ZnO:N) thin films fabricated by radio frequency magnetron sputtering was were studied using x-ray absorption spectroscopy. Structural parameters such as c/a ratio, unit cell volume, inter-atomic distance and mean-square displacement were calculated by the fitting extended x-ray absorption fine structure (EXAFS) data measured at Zn K edge to a fully occupied wurtzite structure. Principal component analysis (PCA) was utilized to analyze relationships among variables and to differentiate thin film samples based on their structural profiles. It was found that local environment around Zn atoms changed moderately due to N doping and deposition conditions. In particular, lattice-related parameters were strongly correlated with each other and tended to be uncorrelated with mean-square displacements. Information on the local structure for each ZnO:N sample can be represented in a PCA score plot in which samples could be differentiated by their profiles or deposition methods.

In this work, a reactive DC magnetron sputtering using a glancing-angle deposition (GLAD) was performed for the fabrication of vertically aligned tungsten oxide (WO3) nanorods. The effect of various Ar flow rates was investigated by observing the physical morphologies of the samples using the field-emission scanning electron microscopy (FE-SEM). The crystal structures were characterized by the grazing-incident X-ray diffraction technique. The FE-SEM images showed that the length and diameter of WO3 nanorods were significantly affected by different Ar flow rates used in the sputtering process. Therefore, the Ar flow rate is a crucial factor for the modification of the physical morphologies and the optical properties of the WO3 nanorods.

In this present work, the copper oxide (CuO) thin films were deposited by dc reactive magnetron sputtering on silicon (100) wafer. The microstructural evolution of the CuO thin films were investigated as a function of film thickness at the range of 150 to 600 nm by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The optical transmittance was measured by UV-VIS-NIR spectrophotometer. The sheet resistances of the CuO thin films were characterized by four-point-probe measurement. The results indicated that the obtained films were polycrystalline. The surface roughness of the CuO thin film showed an increasing with film thickness. In addition, the relationship between film thickness, morphology and electrical property were discussed in this paper.

The Copper thin films were grown on glass slide and silicon wafer substrate by DC reactive magnetron sputtering with a 99.995% pure copper target. The distance between substrate and target was varied from 87 to 117 mm. The structural, morphology and electrical properties of the prepared samples were investigated by X-ray diffraction (XRD), field-emission electron microscope (FE-SEM) and four-point-probe, respectively. All of the prepared samples were polycrystalline with a monoclinic tenorite. In addition, as the distance from substrate and target decreases further, the grain size increases and sheet resistance decreases.

Aluminum oxide thin films produced by reactive sputtering processes are widely used in optical and microelectronic applications. This work investigates the dependency of the films’ surface roughness (Ra) on the operating pressure, the sputtering power and the deposition technique. Amorphous aluminum oxide thin films were grown on silicon (100) wafers by the DC and RF reactive magnetron sputtering deposition processes. In this experiment, high purity Al target (99.999%) was used. The operating pressures were set to 3, 5 and 10 mTorr. The sputtering powers were adjusted to 150 W and 300 W. Oxygen was injected into the chamber to react with sputtered Al atoms and formed aluminum oxide. For DC reactive magnetron sputtering, it was found that the surface roughness increased with increasing operating pressure. For the sputtering power of 300 W, the surface roughness increased from 1.03 nm to 2.17 nm as the operating pressure changed from 3 mTorr to 10 mTorr, respectively. It was also found that lower sputtering power resulted in smoother films. At 150 W sputtering power and 3 mTorr operating pressure, the Ra value was measured to be 0.81 nm. Higher operating pressure and sputtering power resulted in higher rates of particle collisions and scatterings. This reduced energies of sputtered atoms, preventing them to form dense and smooth films. The film deposited by the RF reactive magnetron sputtering yielded the lowest Ra value. At 150 W sputtering power and 3 mTorr operating pressure, the Ra value of the film was found to be 0.49 nm.

Thermoelectric generators harvest energy from waste heat and convert it to electricity. β-Cu2Se is a candidate for them due to its outstanding thermoelectric properties and its environmentally friendly component elements. A microwave hybrid heating (MHH) method was used for the fast synthesis and enhancement of β-Cu2Se materials. The effects of the MHH reaction time on the phase microstructure and thermoelectric properties of the Cu2Se material were investigated, and the MHH method was compared with the conventional heating method. The X-ray diffraction patterns of samples, synthesized via the MHH method, showed monoclinic- (α) and cubic- (β) Cu2Se crystalline structures, whereas a single monoclinic-(α) structure was identified in a sample, synthesized via a conventional heating method. In addition, the β-Cu2Se phase was enhanced with increased MHH reaction time. The carrier concentration increased with β-Cu2Se content, which increased electrical conductivity and decreased the Seebeck coefficient. The Cu+ ions in the β-Cu2Se phase led to the reduced thermal conductivity. A low thermal conductivity of 0.86 W m−1 K−1 and a maximum dimensionless figure of merit of 0.32 at 523 K were realized for 10 min MHH sample. Finally, MHH showed very low energy consumption and saved time, which are essential for industrialization.

Electrospun Ag-incorporated WO3 nanofibers were prepared as recyclable surface-enhanced Raman scattering (SERS) substrates. The entangled mats of the nanofibers offered large specific surface areas with the Raman hotspots expanded in the third dimension. Their SERS activities were measured using methylene blue (MB) as a test substance. The substrates yielded an enhancement factor of 6.2 × 105 and exhibited good reproducibility (RSD of 10.35 %). The limit of detection (LOD) was found to be 10−5 M. The resulting nanofibers showed recyclability induced by photocatalytic degradation of adsorbed MB molecules under visible light. The Ag-incorporated WO3 nanofibers demonstrate themselves as promising platforms for the development of large-scale SERS substrates with recyclability and high-density hotspots.

Spectroscopic ellipsometry (SE) was used to characterize the effect of the CO2/SiH4 ratios on the p-type hydrogenated microcrystalline silicon oxide (p-μc-SiOx:H) thin films. The p-μc-SiOx:H thin films were fabricated by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) method on the soda-lime glass substrates. The CO2/SiH4 ratios were varied from 0.0 to 0.5 with constant H2-dilution during the deposition. The p-μc-SiOx:H samples were analyzed for thickness, microstructure, and optical characteristics by SE. The ellipsometric measurements were performed in the range of 0.75–5.5 eV with the incident angle of 50, 60 and 70 degrees. The physical structures were proposed as either the double- and triple-layer models. The optical dispersion was proposed based on Tauc-Lorentz (TL) model in order to extract the information of interest including dielectric dispersion and crystalline fraction. The results from the SE analyses showed that the thin films prepared with pure SiH4 could only be fitted by the triple-layer model, whose effect refractive index was gradually decreased from 3.92 to 2.53 with the increased CO2/SiH4 ratio. With the introduction of the CO2, the obtained films were instead best represented by the double-layer model. The calculated crystalline fractions could be determined from the SE results, which accurately corresponded to those from the Raman spectroscopy and high-resolution transmission electron microscope (HRTEM). In addition, the dielectric dispersion of the thin films was related directly with CO2/SiH4 ratios, but inversely with crystalline fraction with the values of 53 down to 18% with the increased gas mixture ratio.

In this work, flexible Bi x Te y thin films were prepared by radio frequency (RF) magnetron sputtering using a Bi2Te3 target on polyimide substrate. The effects of sputtering pressures, which ranged between 0.6 Pa and 1.6 Pa on the [Bi]:[Te] ratio, and structural and thermoelectric properties were investigated. The [Bi]:[Te] ratio of thin film was determined by energy-dispersive spectrometry (EDS). The EDS spectra show the variation of the [Bi]:[Te] ratio as the sputtering pressure is varied. The film deposited at 1.4 Pa almost has a stoichiometric composition. The selective films with different [Bi]:[Te] ratios and sputtering pressures were characterized by their surface morphologies, crystal and chemical structures by field emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD) and Raman spectroscopy, respectively. Electrical transport properties, including carrier concentration and mobility, were measured by Hall effect measurements. Seebeck coefficients and electrical conductivities were simultaneously measured by a direct current four-terminal method (ZEM-3). The XRD and Raman spectroscopy results show a difference in microstructure between BiTe and Bi2Te3 depending on the [Bi]:[Te] ratio. Electrical conductivity and Seebeck coefficient are related to the crystal and chemical structures. The maximum power factor of the Bi2Te3 thin film is 9.5 × 10−4 W/K2 m at room temperature, and it increases to 12.0 × 10−4 W/K2 m at 195°C.

In this work, high-performance electrochemical energy storage electrodes were developed based on nickel oxide (NiO)-coated nickel (Ni) foams prepared by a sparking method. NiO nanoparticles deposited on Ni foams with varying sparking times from 45 to 180 min were structurally characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. In addition, the electrochemical energy storage characteristics of the electrodes were evaluated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. It was found that NiO nanoparticles sparked on Ni foam with a longer time would be agglomerated and formed a foam-like network with large pore sizes and a lower surface area, leading to inferior charge storage behaviors. The NiO/Ni foam electrode prepared with the shortest sparking of 45 min displayed high specific capacities of 920 C g-1 (1840 F g-1) at 1 A g-1 and 699 (76% of 920) C g-1 at 20 A g-1 in a potential window of 0-0.5 V vs. Ag/AgCl as well as a good cycling performance with 96% capacity retention at 4 A g-1 after 1000 cycles and a low equivalent series resistance of 0.4 Ω. Therefore, NiO/Ni foam electrodes prepared by the sparking method are highly promising for high-capacity energy storage applications.

Based on the Raman spectrocopy of the nanostructure-based SERS chips, the trace amount of methamphetamine and its primary metabolite, i.e., amphetamine, were successfully identified from human urine. The SERS substrates were self-assembled vertically-aligned silver nanorods prepared by the magnetron sputtering technique. The matrix spikes of the human urine specimens were prepared to simulate those of the methamphetamine abusers. With the acidulation treatments to the specimen samples, the organic urea-based byproducts were clearly separated. The remaining dissolved methamphetamine/amphetamine in the urine specimens could therefore be enhanced for the SERS analyses, without any interference from the urea. The performance of the proposed acidulation treatments toward the SERS detections of the matrix-spike human urine specimens yielded the detection limit at 50 ng/mL.

Growths of the indium tin oxide (ITO) nanorod films have been demonstrated by ion-assisted electron-beam evaporation with the glancing-angle deposition technique based on variation in deposition rate. Investigations have been performed on nanostructured ITO films deposited on ITO-coated commercial substrates in comparison to bare substrates. The physical microstructures have been investigated by grazing-incident X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). The electrical, optical, and hydrophobic properties were characterized by four-point probe measurements, UV–Vis–NIR spectrophotometry with angle-dependent technique, and contact angle goniometry, respectively. The results indicated that physical morphologies and nanorod diameters of ITO nanorod films were heavily influenced, and thus could be controlled, by deposition rate. The primary reason was self-annealing effect which occurred during film deposition and was crucial factor towards surface diffusion and film crystallinity. From the optical examinations, ITO nanorods deposited on the ITO-coated glasses exhibited significant improvements on transparent conductive oxide (TCO) properties from reference samples. The proposed ITO materials could therefore function as omnidirectional anti-reflection materials and super hydrophobic surface. This work have also proved that the ITO nanorods prepared by the electron-beam evaporation with the GLAD technique was highly promising for solar cell and optoelectronic applications.

Transparent conductive aluminum-doped zinc oxide (ZnO:Al or AZO) thin films were fabricated by the pulsed DC magnetron sputtering deposition. The prepared AZO thin films were carefully treated with the argon plasma treatments in the vacuum state with a variety of the plasma conditions, i.e., the control power and the operated pressure. The plasma-treated AZO samples were then investigated for their crystal structures by X-ray diffraction (XRD). Their physical morphologies and surface topologies were examined by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Electrical properties of the samples were measured with the four-point probe and the Hall effect measurements. Finally, their optical transmission was observed with the UV-Vis-NIR spectrophotometry. The results from the as-deposited and the plasma-treated AZO thin films will be compared and discussed.

Tungsten oxide (WO 3 ) is widely applied as an electrochromic layer for several smart window applications. The objective of this research is to develop the nanostructure of WO 3 films with high electrochromic response. The one dimensional nanostructure of WO 3 films was prepared by glancing-angle deposition (GLAD) technique; the tungsten oxide nanorods (WO 3 NRs) were deposited onto indium tin oxide substrate by DC reactive magnetron sputtering. The effect of oxygen flow rate on the properties of WO 3 NRs films was investigated by varying the oxygen flow rate from 12 - 30 sccm, during the deposition of the films. Then, the electrochromic property, the coloring-bleaching and the morphological of the films were characterized by cyclic voltammetry (CV), spectrophotometry and field-emission scanning electron microscopy (FESEM), respectively. We study the effect of ion insertion into the WO 3 NRs by varying the doping ions - H + , Na + and Li + - and measuring the property by CV. The results showed that the insertion of H + into the WO 3 NRs films is faster than that of the others. Moreover, the CV peak and the film transmittance different between coloring and bleaching periods indicated that the electrochromic response increased as the oxygen flow rates were increased. In addition, the nanorods of the WO 3 films were confirmed by FESEM. The influence of oxygen flow rate on morphology and electrochromic property has been discussed.

In this paper, we experimentally demonstrated the oblique angle deposition silicon dioxide nanorods as good anti-reflection coating materials. The nanostructures morphologies and the optical properties were characterized by field-emission scanning electron microscopy and transmission electron microscopy. The influence of the OAD on the optical property of the SiO 2 dense and SiO 2 nanorods film were investigated by the spectral transmission measurement in 200-1200 nm wavelength regimes. The angle-dependent transmission from 0° to 45° incident angles results demonstrate that increased transmittance through the SiO 2 nanosrods surface compared to that of the SiO 2 films coated glass. The SiO 2 nanorods with 800 nm-thick have transmission closed to the SiO 2 film and glass substrate. In addition, the high transmission was observed for angles of incidence up to 45°. The SiO 2 nanorods array makes this omnidirectional antireflection concept easily applicable to a wide range of devices.

Iron nitride (FeN) thin films were deposited on silicon wafer substrates by dc reactive magnetron sputtering techniques. The FeN thin films were prepared at the fixed substrate temperature 200°C under different nitrogen flow rates. The crystal structures, physical morphologies, and surface roughness of the prepared FeN thin films were characterized by the grazing-incident X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM), respectively. From the results, the GIXRD patterns indicated the change in the film orientations from ξ-Fe2N to γ”-FeN along with the increased nitrogen flow rates. In addition, the FE-SEM micrographs demonstrated the decrease of the FeN film thickness. The effects of the nitrogen flow rates towards the crystallinity, the physical morphology, and surface roughness of the thin films were investigated and discussed.

In this work, the tungsten trioxide (WO 3 ) films were prepared on ITO glass by reactive dc magnetron sputtering. The effects of oblique angle deposition (OAD) between 0 – 85° were investigated for optical and morphological properties of WO 3 films and its electrochromic application. The crystal structure, morphologies and optical properties were characterized by grazing – incidence X-ray diffraction, field emission scanning electron microscopy and spectrophotometer, respectively. All WO 3 films exhibited amorphous structure and the WO 3 nanorod morphologies were demonstrated when the OAD more than 60°. It is owing to the shadowing effect and limits adatom diffusion. The electrochromic property of WO 3 films was investigated for colored and bleached states with their optical transmission. It was found that WO 3 nanorod structure prepared by OAD exhibited good electrochromic property due to very large effective surface area and more ion insertion in WO 3 nanorod films. In addition, WO 3 nanorod film prepared by OAD at 80° exhibited an optimum electrochromic property with optical contrast of 62%.

Indium doped tin oxide (ITO) nanostructured films were prepared by the electron-beam evaporation with the oblique-angle deposition (OAD) technique. The influence of the film thickness of the ITO nanostructures on the crystal structures, the physical morphologies, the optical properties, and the electrical attributes was investigated by grazing-incident X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM), UV-Vis spectrophotometry, four-point probe measurements, the respectively. The GIXRD analyses indicated that the ITO nanostructured films were mostly polycrystalline with the cubic bixbite structure. The FE-SEM micrographs clearly showed that the increased film thickness greatly affected the morphologies of the ITO nanostructures. The optical transmission spectra at the different angles of incidence clearly demonstrated the optimized results for the highest transmission in the visible region. The electrical resistivity of the ITO nanostructures was gradually decreased with the increased ITO thickness. Finally, the most optimized solar transmission with small light scattering and sheet resistance were discussed based on the anti-reflection performance of the ITO nanostructured films towards the solar cell applications.

Zinc oxide (ZnO) nanorods (NRs) were fabricated via the hydrothermal method at 90°C for 6 hour on the substrates with the ZnO seed layers. The ZnO seed layers had previously prepared at the different thickness, whose effects on the ZnO NRs were investigated. On the prepared ZnO samples, the morphologies and the crystal structures were examined by field-emission scanning electron microscopy and X-ray diffraction, respectively. The results show that the thickness of the seed layers directly affected on their crystallinity, the surface roughness and the ZnO NRs structures. From the hydrothermal process, the ZnO NRs grown on the seed layers with the smooth surface showed the well-aligned nanorod patterns. In addition, the growth rate of the ZnO NRs was also greatly affected by the seed layer thickness because of the corresponding surface energy. Finally, the optimizations of the uniformity and high aspect ratios of the ZnO NRs were carefully investigated and discussed.

The tantalum oxide (Ta 2 O 5 ) thin films were prepared by the ion-assisted electron-beam evaporation system. With the fixed film thickness at 200 nm, the deposition conditions were performed based on oxygen flow rate the ion assistance during the film deposition. The prepared thin films were characterized by spectroscopic ellipsometry in order to determine their physical and optical properties. From the ellipsometric measurements, the physical structures of the thin films and the optical dispersions were constructed, and then analyzed for the results of film thickness and optical constants. The thin films were also measured by the UV-Vis-NIR spectrophotometry for the optical transmission. The measured transmission was analyzed with the Swanepoel method, whose results also yielded the thickness and the refractive index. Finally, the thin films were examined by the scanning electron microscopy (SEM) in order to observe physical microstructures. This study explored the physical and optical analyses based on the spectroscopic ellipsometry and the spectrophotometry, with the confirmations from the SEM micrographs. The results from the analyses would be compared and thoroughly discussed.

In this study, we investigated the effects on the film thickness of the vertically aligned indium-doped tin oxide nanorods (ITO NRs). The ITO nanorods of deposited time at 180 to 780 sec were deposited on the silicon wafers and ITO-coated glass substrate by the ion-assisted electron-beam evaporation with the glancing-angle deposition technique. The physical microstructures and optical properties of the prepared samples have been investigated by grazing-incident X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM), and spectrophotometry. From the results, the ITO nanorods indicated the bixbite structures. The FE-SEM micrographs showed the changes of the physical morphologies based on the increased film thickness. The angle-dependent transmission as measured from -80° to 80° incident angles demonstrated the increased optical transmission from the vertically aligned ITO nanorods, compared to that of the ITO-coated glass. The enhancement of the optical transmission was related to the anti-reflection and light-scattering properties of the ITO nanorods, and offered a great potential for solar cell applications.

Titanium dioxide (TiO 2 ) nanorods were deposited on glass slide and silicon wafer substrate by glancing angle deposition method. The influence of the substrate rotation speed from 10 to 30 rpm on the structure, morphology, optical transmission and wettability were investigated by x-ray diffractometer, field emission spectroscopy, spectrophotometer and contact angle measurement. The results were shown that all prepared samples have amorphous structure. By varying the substrate rotation speed, the TiO 2 has a different nanostructure. In addition, the surface of the TiO 2 nanorods deposited at 10 rpm was highly hydrophobic property with a water contact angle of 38 degree. The origin of the different wetting properties for TiO 2 nanorods films were discussed in this report.