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Multifunctional monoclinic VO2 nanorod thin films for enhanced energy applications: Photoelectrochemical water splitting and supercapacitor
摘要： Monoclinic VO2 nanorod thin films were deposited on indium?tin-oxide-coated glass substrates using radio-frequency reactive magnetron sputtering at a substrate temperature of 300 °C and various O2 flow rates. The thin films were characterized via standard analysis techniques. The VO2 thin films exhibited a highly crystalline monoclinic phase with an indirect band gap of ~1.73 eV. At optimized O2 flow rate (4 sccm), the thin films was observed nanorod structures, exhibited a remarkable photocurrent of ~0.08 mA cm?2 during photoelectrochemical water splitting in the visible region. Electrochemical performance tests of the nanorod films revealed a specific capacitance of ~486 mF cm?2 at a scan rate of 10 mVs?1. In addition, amperometric I–t curves showed that VO2 thin film electrodes were highly stable during the photo-oxidation process. The nanorod films also exhibited a good specific capacitance of ~120 mF cm?2 after 5000 cycles at a scan rate of 100 mVs?1. The photocurrents during photoelectrochemical water splitting and the specific capacitance of VO2 thin films deposited at O2 flow rates of 2 and 6 sccm were 0.06 and 0.07 mA cm?2 and 398 and 37 mF cm?2, respectively. The films deposited under Ar at 8 sccm and O2 at 4 sccm showed the highest photoelectrochemical water splitting performance and specific capacitance, owing mainly to their nanorod-like morphology.
关键词： Supercapacitor,Partial pressure,Reactive sputtering,Photoelectrochemical water splitting,VO2,Monoclinic
更新于2025-09-23 15:22:29
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Effect of temperature and bias voltage on electrical and electrochemical properties of diamond-like carbon films deposited with HiPIMS
摘要： The relatively high electrical resistivity of diamond-like carbon (DLC) film is one of the main drawbacks when applied in electronic device. In this study, DLC films were synthesized on 304 stainless steels by high power impulse magnetron sputtering (HiPIMS) process and the effect of deposition temperature and bias voltage on the microstructure, electrical and electrochemical properties, hardness and adhesion strength of the DLC films were investigated. The sp2/sp3 ratio of DLC films first decreased then increased and the surface became denser as bias voltage increasing from 0 to -400 V. While the film turned into graphite-like structure and became incompact when deposition temperature rose from 100 °C to 300 °C. The interfacial contact resistance (ICR) got reduced by increasing bias voltage and deposition temperature. However, as the deposition temperature increased to 300 °C the anticorrosion ability and hardness of DLC films deteriorated. The DLC films deposited at 300 °C presented soft and had better adhesion strength than hard DLC films deposited at 100 °C. DLC films deposited at -400 V bias and 300 °C had the lowest ICR while DLC films deposited at -400 V bias and 100 °C had the best performance when ICR, corrosion resistance and hardness were all taken into consideration.
关键词： Electrochemical corrosion,Substrate temperature,High power impulse magnetron sputtering,Interfacial conductivity,Diamond-like carbon,Bias voltages
更新于2025-09-23 15:22:29
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Influence of gold nanolayer coating on the continuous-wave laser ablation of a pure aluminum surface: Evaluations of structural and optical features
摘要： In this paper, formation of uniform and large-area micro/nanostructures on pure aluminum surfaces using a continuous-wave laser irradiation is presented. Gold nanolayer coating was utilized as a confinement layer for controlling the possible hydrodynamic phenomena in a molten area. Dependency of the laser-induced morphology on the thickness of a gold coating was investigated in this regard. Scanning electron microscopy, energy dispersive spectroscopy, grazing test of the X-ray diffraction, and optical absorption/reflection spectroscopy in UV/visible/IR ranges were employed to characterize the samples. Results showed that the formation of uniform structures of average sizes of 50 nm-5μm on aluminum surface was possible following the irradiation of a continuous-wave CO2 laser, delivering 130 W beam power. Alterations of the surface morphology brought about an increase in specific absorption peaks at the UV region and the appearance of an absorption peak in the visible range. In addition, these structure-covered surfaces provided interesting reflection behaviors in different spectral areas, which can clearly reflect their high potential to be used as selective solar absorbers. The results of this investigation indicated that optical characteristics such as absorption and emission coefficients as well as ξ factor were 0.98, 0.13, and 7.53, respectively. It can therefore be concluded that this process can be considered an efficient and fast technique to fabricate selective solar absorbers.
关键词： Nanostructures,Aluminum,Selective solar absorber,Sputtering,Nanolayer,Continuous-wave CO2 laser,Gold,Black carbon
更新于2025-09-23 15:22:29
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Towards fast and highly responsive SnSe <sub/>2</sub> based photodiode by exploiting the mobility of the counter semiconductor
摘要： In photodetection, the response time is mainly controlled by the device architecture and electron/hole mobility, while the absorption coefficient and the effective separation of the electrons/holes are the key parameters for high responsivity. Here, we report an approach towards the fast and highly responsive infra-red photodetection using n-type SnSe2 thin film on p-Si (100) substrate keeping the overall performance of the device. The I-V characteristics of the device show a rectification ratio of ~147 at ± 5 V and enhanced optoelectronic properties under 1064 nm radiation. The responsivity is 0.12 A/W at 5 V and the response/recovery time constants were estimated as ~ 57±25/34±15 μs respectively. Overall, the response times are shown to be controlled by the mobility of the constituent semiconductors of a photodiode. Further, our findings suggest that n-SnSe2 can be intergrated with well established Si technology with enhanced opto-electronic properties and also pave the way in the design of fast response photodetectors for other wavelengths as well.
关键词： Selenisation,DC sputtering,IR-Photodiode,SnSe2,Mobility
更新于2025-09-23 15:22:29
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Contact Angle Relaxation and Long-lasting Hydrophilicity of Sputtered Anatase TiO <sub/>2</sub> Thin Films by Novel Quantitative XPS Analysis
摘要： The contact angle relaxation of TiO2 surfaces is an important problem that must be understood, particularly for long-lasting hydrophilicity under dark conditions. The relaxation of sputtered anatase TiO2 thin films over a long time (~22 days) in an atmospheric environment was observed using quantitative XPS analysis. A new peak was identified as H2O within a donor-acceptor complex at ~2.57 eV above the lattice oxygen peak. This donor?acceptor complex turns out to be a key factor for long lasting hydrophilicity, and our model is presented. Adventitious carbon contamination was not the main cause of the contact angle relaxation. Instead, samples with lower amounts of donor?acceptor complexes (IDAC/Ibulk ≤ ~5%) underwent contact angle relaxation over time, and samples with a high density of donor?acceptor complexes (IDAC/Ibulk ≥ ~10%) showed good hydrophilicity (contact angle ≤ 20°) over 22 days. Larger amounts of basic Ti?OH relative to acidic OHbridge (ITi?OH/Ibridge ≥ 1) resulted in greater amounts of donor?acceptor complexes (IDAC/Ibulk ≥ ~10%). Thus, basic Ti?OH groups interact with H2O by forming a strong electrostatic donor?acceptor complex, leading to long-lasting hydrophilicity. Indeed, TiO2 was transformed to show long lasting hydrophilicity by high-density oxygen plasma treatment by forming sufficient Ti?OH groups and H2O molecules in the donor?acceptor complexes. Contact angle relaxation is closely related to the interactions between water molecules and the TiO2 surface in the dark. It is suggested that the relaxation depends on the number of electrostatic donor?acceptor complexes. This study provides new insight by linking theoretical studies with the experimental contact angle at the TiO2 surface in an ambient environment and is the first study that provides the presented relaxation mechanism.
关键词： Hydrophilicity,Sputtering,Plasma treatment,Contact angle relaxation,XPS analysis,Donor-acceptor complex,TiO2 thin films
更新于2025-09-23 15:22:29
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‘Planetary’ silver nanoparticles originating from a magnetron sputter plasma
摘要： In a gas aggregation cluster source, nanoparticles are formed by aggregation of single atoms to particles as well as by agglomeration of smaller particles to form larger particles. Because the small particles are often electrically charged, it is possible that particles are mutually attracted or repelled by electric forces. In this work we report the observation of bound multi-nanoparticle systems which are the result of the electrical and centrifugal forces acting on nanoparticles in a magnetron sputtering cluster source. Transmission electron microscopy analysis of the deposited ‘planetary’ nanoparticle systems exhibits characteristic inter-particle distances and sizes, consistent with different charge states of the particles. Simulations confirm the presence of metastable bound nanoparticle systems up to at least 7/8 satellites. The discovery of such ‘planetary’ nanoparticle systems inside a cluster source opens up possibilities for more research into their properties and how they can be further controlled and explored.
关键词： planetary,silver nanoparticles,particle orbits,satellites,gas aggregation cluster source,magnetron sputtering
更新于2025-09-23 15:22:29
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Study of the effect of irradiation with Fe<sup>7+</sup> ions on the structural properties of thin TiO<sub>2</sub> foils
摘要： Thin foils based on the TiO2 phase of brookite, 620 nm thick, were obtained by magnetron sputtering. The samples were irradiated at the DC-60 heavy ion accelerator of the Astana branch of the Institute of Nuclear Physics with Fe7+ ions with an energy of 85 MeV with a fluence of 1×1011 to 1×1014 ions/cm2. The dependences of the change in the concentration of defects in the structure of thin films on the radiation dose are established. It has been established that an increase in the irradiation fluence of up to 1014 ions/cm2, characteristic of the formation of defect overlap regions, leads to a sharp decrease in the degree of crystallinity and an increase in the lattice parameters. That is caused by the formation of a large number of disorder regions and displaced atoms in the structure, which migrate along the crystal lattice to additional distortions and voltages, with the subsequent formation of hillocks.
关键词： ionizing radiation,thin foils,crystal structure defects,magnetron sputtering
更新于2025-09-23 15:22:29
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PdEr-Silicide Formation and Contact Resistivity Reduction to n-Si(100) Realized by Dopant Segregation Process
摘要： In this paper, we have investigated the PdEr-silicide formation utilizing a developed PdEr-alloy target for sputtering, and evaluated the contact resistivity of PdEr-silicide layer formed on n-Si(100) by dopant segregation process for the first time. Pd2Si and ErSi2 have same hexagonal structure, while the Schottky barrier height for electron (Φbn) is different as 0.75 eV and 0.28 eV, respectively. A 20 nm-thick PdEr-alloy layer was deposited on the n-Si(100) substrates utilizing a developed PdEr-alloy target by the RF magnetron sputtering at room temperature. Then, 10 nm-thick TiN encapsulating layer was in-situ deposited at room temperature. Next, silicidation was carried out by the RTA at 500°C for 5 min in N2/4.9%H2 followed by the selective etching. From the J-V characteristics of fabricated Schottky diode, qΦbn was reduced from 0.75 eV of Pd2Si to 0.43 eV of PdEr-silicide. Furthermore, 4.0x10?8Ωcm2 was extracted for the PdEr-silicide to n-Si(100) by the dopant segregation process.
关键词： contact resistivity,PdEr-alloy target,RF magnetron sputtering,schottky barrier height,silicide
更新于2025-09-23 15:22:29
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Influence of Local Heterojunction on the Thermoelectric Properties of Mo-SnSe Multilayer Films Deposited by Magnetron Sputtering
摘要： Mo-SnSe multilayer films were deposited by multi-step magnetron sputtering. The Mo-SnSe multilayer films are then annealed, and the new phases including SnSe2 and MoSe2 are observed by x-ray diffraction and Raman spectroscopy. Scanning electron microscopy reveals that the SnSe exhibits the columnar grain structure with sizes from 50–100 nm. The high-resolution transmission electron microscopy shows the SnSe2 is dispersed at the boundary of the columnar grain and the local MoSe2/SnSe heterojunction is formed in the interior of the columnar grain. The influence of Mo content on the thermoelectric properties of SnSe thin films was investigated. A maximum power factor of 0.44 μW cm?1 K?2 was obtained for a 2.6 at.% Mo-doped SnSe thin film at 576 K, which is higher than that of a SnSe thin film deposited under the same conditions.
关键词： thermoelectric properties,heterojunction,SnSe films,sputtering
更新于2025-09-23 15:22:29
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Analysis of the Mo/Mo Nanocrystalline Optical Coating Obtained with the Aid of Simultaneous Deposition and Ion Sputtering
摘要： Structure, optical properties, and resistance to sputtering are studied for a reflecting Mo-coating that is fabricated using magnetron deposition with simultaneous low-energy ion sputtering at the deposition rate that is higher than the etching rate. A Mo-polycrystalline mirror is used as a substrate. It is shown that the coating exhibits textured nanocrystalline structure with a relatively low spread of crystallite sizes and high resistance to sputtering. It is also demonstrated that the spectral reflection coefficient of such a Mo-coating differs from the spectral reflection coefficient of polycrystalline and single-crystalline Mo and the difference results from the effect of the structure of coating on its optical properties. A theoretical model of the coating formation is proposed.
关键词： optical properties,Mo-coating,nanocrystalline structure,ion sputtering,magnetron deposition,resistance to sputtering
更新于2025-09-23 15:21:21