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Thickness-modulated thermochromism of vanadium dioxide thin films grown by magnetron sputtering
摘要： Vanadium dioxide (VO2) films were prepared on soda-lime glass by direct current magnetron sputtering at 320 °C. Effects of film thickness on the microstructure, surface morphology and thermochromic performance of VO2 films were investigated. X-ray diffraction showed that the deposited films have strong preferred orientation of VO2 (011) lattice when the film thickness higher than 102 nm. The calculated grain sizes of VO2 films increased from 16.05 nm to 34.56 nm continuously with the increasing of film thickness. UV/VIS/NIR spectrophotometer showed that the visible transmittance deceased while the infrared transmittance switching efficiency increased as the film thickness increased from 79 nm to 264 nm. Additionally, the optical band gaps of VO2 films were in a range of 1.15 eV–1.40 eV, and the thicker film exhibited the smaller value. Moreover, the results of measured temperature-dependent electrical resistivity of these VO2 films showed that the phase-transition temperature is in a range of 53–60 °C, which is much lower than that of single-crystal VO2 (68 °C). With the film thickness increasing, the metal–semiconductor phase transition becomes more obvious. Overall, films with thickness in the range of 80–100 nm showed comparatively relatively balanced combination of visible transmittance and solar switching efficiency.
关键词： Thermochromic performance,Film thickness,Vanadium dioxide,Magnetron sputtering
更新于2025-09-23 15:23:52
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CdZnTe thick film radiation detectors with B and Ga co-doped ZnO contacts
摘要： High quality CdZnTe thick films were prepared on boron and gallium co-doped ZnO (BGZO) transparent conductive films by using close-spaced sublimation (CSS) method. Due to its high stability, hardness and similar thermal expansion coefficient with CdZnTe, BGZO films were also used to replace the traditional metal to form good ohmic contact with CdZnTe. CdZnTe thick film radiation detectors with BGZO/ CdZnTe/ BGZO structure were fabricated. The results showed a well response of the CdZnTe thick film detector (the energy resolution is about 25%) from a 60KeV 241Am γ-source.
关键词： close-spaced sublimation,CdZnTe thick film,detector,ZnO
更新于2025-09-23 15:23:52
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Effect of post-annealing on microstructure and piezoelectric properties of ZnO thin film for triangular shaped vibration energy harvester
摘要： In this paper, a triangular shaped piezoelectric vibration energy harvester (TS-PVEH) with zinc oxide (ZnO) thin films as the piezoelectric layer is reported. The effect of post-annealing temperature on the microstructure and piezoelectric performance of ZnO thin film deposited by magnetron sputtering method is investigated firstly. The results show that the optimum post-annealing temperature of 150 °C was the most beneficial to improve the piezoelectric properties of ZnO thin films. Four prototypes of TS-PVEH with different structure parameters are fabricated and optimized. The simulation and experiment results indicate that the height and width of the triangular structure have a significant influence on the vibration mode and the output performance of TS-PVEHs. The optimization results indicate that the third prototype has the best output performance. Its open-circuit voltage and short-circuit current are 290mV and 1.25 μA, respectively, when the vibration acceleration is 5m/s2 and the frequency is 56Hz. Moreover, it has the highest load power density of 0.035μW/cm2 when the load is 0.1MΩ.
关键词： Triangular substrate,ZnO thin film,Structure optimization,Post-annealing temperature,Vibration energy harvester
更新于2025-09-23 15:23:52
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Preparation of multicomponent thin films by magnetron co-sputtering method: The Cu-Ti case study
摘要： The paper discusses the preparation of multicomponent thin films of Cu-Ti composite with desired elemental composition using the pulsed magnetron co-sputtering technology. The technological goal described in the paper was deposition the Cu-Ti composite with elemental ratio of about 50/50 at.%, which is close to the eutectic point from the Cu-Ti alloy system. A large difference in the sputtering yield (about seven-fold) of Cu and Ti metals was challenging, because of the features of used power supplies. Desired concentrations of the Ti and Cu elements were obtained as a result of application of multimagnetron sputtering system, where magnetrons were equipped with the Ti or Cu targets. Additionally, pulse power supply was used together with the pulse width modulation controller. Moreover, the article presents investigations of structural and mechanical properties of deposited Cu, Ti and Cu-Ti films with elemental composition of ca. 50/50 at.%. It was found that the two component Cu0.5Ti0.5 thin films were composed of Cu4Ti3 nanocrystallites built-in an amorphous matrix. As compared to the pure Cu and Ti thin films, the prepared composite exhibited improved hardness and better elasticity reflected in lower values of the Young’s modulus. The results of nanoindentation investigations showed that the Cu0.5Ti0.5 composite thin film was characterized by the hardness of 7.59 GPa.
关键词： thin film,CuTi alloy,multicomponent coating,magnetron sputtering
更新于2025-09-23 15:23:52
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The finite size effect on the transport and magnetic properties of epitaxial Fe <sub/>3</sub> O <sub/>4</sub> thin films
摘要： Magnetite (Fe3O4) has great potential for use in the new field of spintronics due to its interesting physical properties, e.g., half-metallic ferromagnetic nature and metal–insulator transition (Verwey transition). Therefore, a basic understanding of these properties is essential for applications in spintronics devices, especially as the film thickness is reduced. In this work, the transport and magnetic properties of stoichiometric ultra-thin epitaxial Fe3O4 films have been investigated. The Fe3O4 films were grown on MgO (001) substrates using molecular beam epitaxy under optimal growth conditions. Low energy electron diffraction and X-ray photoemission spectroscopy confirmed that the films are single phase Fe3O4. The Verwey transition has been investigated using both transport and magnetization measurements. The magnetization measurements show a sharp Verwey transition in all of these films, which indicates that the films have properties comparable to the bulk. Furthermore, the magnetization measurements at room temperature show that the ultrathin films with thickness t < 20 nm are ferromagnetic with magnetization values greater than those for bulk magnetite. Such enhanced magnetization in ultrathin Fe3O4 films is very promising for spin injection and other applications.
关键词： Verwey Transition,Epitaxial Growth,Magnetization,Fe3O4,Thin Film
更新于2025-09-23 15:23:52
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Proposal of Novel Optical Model for Light-Diffusing Film Having Alternating Polymer Layers with Different Refractive Indices
摘要： We have proposed the novel optical model for layer structure film to precisely control light diffusion angle range. By introducing structure characteristics to the phase grating model, we successfully constructed the novel optical model. In addition, we clarified that difference of refractive indices of layer structure and layer width are important factors for precisely control of light diffusion angle range.
关键词： diffraction,light-diffusing film,optical model,refractive index,layer structure
更新于2025-09-23 15:23:52
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Optimised Performance of Non-Dispersive Infrared Gas Sensors Using Multilayer Thin Film Bandpass Filters
摘要： In this work, performance improvements are described for a low-power consumption non-dispersive infrared (NDIR) methane (CH4) gas sensor using customised optical thin film bandpass filters (BPFs) centered at 3300 nm. BPFs shape the spectral characteristics of the combined mid-infrared III–V based light emitting diode (LED)/photodiode (PD) light source/detector optopair, enhancing the NDIR CH4 sensor performance. The BPFs, deposited using a novel microwave plasma-assisted pulsed DC sputter deposition process, provide room temperature deposition directly onto the temperature-sensitive PD heterostructure. BPFs comprise germanium (Ge) and niobium pentoxide (Nb2O5) alternating high and low refractive index layers, respectively. Two different optical filter designs are progressed with BPF bandwidths (BWs) of 160 and 300 nm. A comparison of the modelled and measured NDIR sensor performance is described, highlighting the maximised signal-to-noise ratio (SNR) and the minimised cross-talk performance benefits. The BPF spectral stability for various environmental temperature and humidity conditions is demonstrated.
关键词： III–V,sensor,methane,thin film,MBE,NDIR,microwave,bandpass,sputter,heterostructure,infrared
更新于2025-09-23 15:23:52
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Low-Temperature Plasma-Enhanced Atomic Layer Deposition of Tin(IV) Oxide from a Functionalized Alkyl Precursor: Fabrication and Evaluation of SnO <sub/>2</sub> -Based Thin-Film Transistor Devices
摘要： A bottom-up process from precursor development for tin to plasma-enhanced atomic layer deposition (PEALD) for tin(IV) oxide and its successful implementation in a working thin-film transistor device is reported. PEALD of tin(IV) oxide thin films at low temperatures down to 60 °C employing tetrakis-(dimethylamino)propyl tin(IV) [Sn(DMP)4] and oxygen plasma is demonstrated. The liquid precursor has been synthesized and thoroughly characterized with thermogravimetric analyses, revealing sufficient volatility and long-term thermal stability. [Sn(DMP)4] demonstrates typical saturation behavior and constant growth rates of 0.27 or 0.42 ? cycle?1 at 150 and 60 °C, respectively, in PEALD experiments. Within the ALD regime, the films are smooth, uniform, and of high purity. On the basis of these promising features, the PEALD process was optimized wherein a 6 nm thick tin oxide channel material layer deposited at 60 °C was applied in bottom-contact bottom-gate thin-film transistors, showing a remarkable on/off ratio of 107 and field-effect mobility of ≈ 12 cm2 V?1 s?1 for the as-deposited thin films deposited at such low temperatures.
关键词： thin-film transistors,tin(IV) oxide,thin films,precursors,atomic layer deposition
更新于2025-09-23 15:23:52
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Tuning Material Properties of ZnO Thin Films for Advanced Sensor Applications
摘要： We report on the growth of ZnO thin films by plasma-enhanced atomic layer deposition as a function of substrate temperature. The method to ensure self-limiting growth with precise thickness control is discussed and the effect of temperature on the texture of the thin films is presented. Switching the texture from (100) to (002) by increasing the substrate temperature is a key property for functional devices. The ZnO thin films with tailored properties could find applications in a wide range of sensors and actuators.
关键词： atomic layer deposition,ZnO,thin film,semiconductor
更新于2025-09-23 15:23:52
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Effects of Withdrawal Speeds on Properties of ZnO Thin Films Prepared by Sol-Gel Immerse Technique
摘要： ZnO thin films have attractive applications in photoelectric device, due to their excellent chemical, electrical and optical properties. In this paper, ZnO thin films with good c-axis preferred orientation and high transmittance are prepared on glass sheets by sol-gel immerse technique. The effects of withdrawal speeds on the growth process of thin film crystal, film crystal orientation and the crystallinity, the optical performance were investigated by XRD, SEM and UV-Vis spectrophotometry. The results show that the thin films were composed of better hexagonal wurtzite crystals with the c-axis prepared orientation. The transmittance of prepared thin films is over 80% in the visible-near IR region from 600 nm - 800 nm. ZnO films have sharp and narrow diffraction peaks, which indicates that the materials exhibit high crystallinity. With the withdrawal speeds increasing, the grain size of ZnO thin films and the intensity for all diffraction peaks were increased gradually. The growth model is changed from the stratified structure into the island structure in the growth process. The transmittance of the thin films decrease in the visible wavelength region, with the withdrawal speeds increasing.
关键词： Withdrawal speeds,ZnO thin film,C-axis preferred orientation,Sol-gel technique
更新于2025-09-23 15:23:52