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Optical properties of SnO2 thin films prepared by pulsed laser deposition technique
摘要： Tin dioxide (SnO2) thin-film has been deposited on a glass substrate by pulsed laser deposition technique under different deposition parameters. The effects of varying the parameters of Q-switched Nd-YAG laser such as laser power, frequency, and laser pulse repetition are studied by examining the optical properties. The pulsed laser-deposited SnO2 films were investigated under both vacuum and an argon background pressure of 10-3 mbar. The optical properties result shows a considerable shift in the optical spectra. The absorption edge in the absorption spectrum at high laser repetition (200 pulses per second) shifts to a higher wavelength region after pumping the argon gas. This indicates pumping the argon gas to the vacuum increasing the absorption of the film. In addition, the transmittance of the films starts at a higher wavelength when pumping argon gas. Increasing the pressure by pumping the argon might influence the film deposition and then might increase the absorption. It also indicates the start of transmittance at a lower energy in the absence of argon gas. The reflectance reduces slowly with increasing the wavelength after pumping the argon gas. This might be attributed to the increase in the vacuum pressure which affects the speediness of the film absorption.
关键词： Tin oxide,Pulsed laser deposition,Optical properties
更新于2025-09-16 10:30:52
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Effect of post deposition annealing on the electrical properties of YSZ thin films deposited by pulsed laser technique
摘要： In this paper we report the detailed analysis of the effect of in-situ annealing on the electrical properties of yttrium stabilized zirconium oxide (YSZ) thin films grown by pulsed laser deposition on silicon substrates. The optimized metal/YSZ/Si devices showed low leakage current, good dielectric strength and a breakdown field strength of 4.13 MV/cm. The magnitudes of flat band voltage, and interfacial charge density have been extracted from the capacitance-voltage (C-V) characteristics of the MOS structure. The C-V characteristics show a small hysteresis which indicates the presence of traps. The observed shift in the flat band voltage and hysteresis are explained with the help of X-ray photoelectron spectroscopy. From the XPS depth profile analysis of the samples it was found that as we go from the surface to the interface, oxygen concentration in the deposited film decreases, i.e. the oxide becomes zirconium rich. This has been correlated with the observed electrical properties.
关键词： Thin films,Interface,Dielectric breakdown,Gate dielectric,Zirconium oxide (ZrO2),Pulsed laser deposition
更新于2025-09-16 10:30:52
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Investigation of nitrogen and iron co-doped TiO2 films synthesized in N2/CH4 via pulsed laser deposition technique
摘要： Nitrogen and iron ions co-doped titania films have been synthesized by PLD technique in nitrogen/methane (N2/CH4) (5:1) media at 1 mbar. Most of the samples are XRD amorphous but a certain amount of crystalline rutile is detected by Raman measurements. The presence of rutile phase only and its low crystallinity degree can be caused by nitrogen doping of oxide matrix. The most intensive VIS absorption and the lowest band gap values are observed for 5% Fe2O3 or Fe3O4 titania films that are supported by the highest nitrogen amount on the surface. The strongest photocatalysts in process of dichromate reduction under either UV or VIS irradiation are shown to be the films obtained from 5% iron oxide in titania target and synthesized at 550 °C as a result of optimal content of Ti–N and Ti–O–Fe structural fragments as revealed by XPS. The presence of Fe3+ and Fe2+ surrounded by oxygen as well as Fe–N bonds is confirmed by XPS data.
关键词： Pulsed laser deposition,Magnetite,Photocatalysis,Hematite,Titania,Nitrogen doping
更新于2025-09-16 10:30:52
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ZnO@TiO2 Core Shell Nanorod Arrays with Tailored Structural, Electrical, and Optical Properties for Photovoltaic Application
摘要： ZnO has prominent electron transport and optical properties, beneficial for photovoltaic application, but its surface is prone to the formation of defects. To overcome this problem, we deposited nanostructured TiO2 thin film on ZnO nanorods to form a stable shell. ZnO nanorods synthesized by wet-chemistry are single crystals. Three different procedures for deposition of TiO2 were applied. The influence of preparation methods and parameters on the structure, morphology, electrical and optical properties were studied. Nanostructured TiO2 shells show different morphologies dependent on deposition methods: (1) separated nanoparticles (by pulsed laser deposition (PLD) in Ar), (2) a layer with nonhomogeneous thickness (by PLD in vacuum or DC reactive magnetron sputtering), and (3) a homogenous thin layer along the nanorods (by chemical deposition). Based on the structural study, we chose the preparation parameters to obtain an anatase structure of the TiO2 shell. Impedance spectroscopy shows pure electron conductivity that was considerably better in all the ZnO@TiO2 than in bare ZnO nanorods or TiO2 layers. The best conductivity among the studied samples and the lowest activation energy was observed for the sample with a chemically deposited TiO2 shell. Higher transparency in the visible part of spectrum was achieved for the sample with a homogenous TiO2 layer along the nanorods, then in the samples with a layer of varying thickness.
关键词： TiO2 thin film,optical properties,ZnO nanorods,chemical deposition,DC reactive magnetron sputtering,pulsed laser deposition,electrical properties,core–shell
更新于2025-09-12 10:27:22
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Improved growth conditions of pulsed laser-deposited PbI2 nanostructure film: towards high- photosensitivity PbI2/CNTs/Si photodetectors
摘要： Nanostructured PbI2 films were grown by laser deposition technique at a substrate temperature of 45?°C was demonstrated. Herein, we attempted to improve and control the crystal growth of PbI2 film and p-PbI2/MWCNTs/p-Si photodetector by finding the optimum laser fluence. X-ray diffraction XRD results illustrate that the grown PbI2 films are polycrystalline with hexagonal structure along (001) and the film crystallinity degraded with increasing the laser fluence. Scanning electron microscope SEM revealed that the particle size decreases as laser fluence increase and film deposited at 3.9?J/cm2 was dense and the grains distributed uniformly over the surface of the film. Energy dispersive X-ray EDX data confirms that the film stoichiometry depends on laser fluence and the film deposited at 3.9?J/cm2 was stoichiometric PbI2. The Photosensitivity investigations reveal that responsivity as high as 0.4 A/W at 610?nm was obtained for the p-PbI2/MWCNTs/p-Si photodetector prepared at 3.9?J/cm2 without post-deposition annealing.
关键词： photodetector,nanostructure film,PbI2,pulsed laser deposition,laser fluence
更新于2025-09-12 10:27:22
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Pure carbon conductive transparent electrodes synthetized by a full laser deposition and annealing process
摘要： One of the biggest challenge that face optoelectronic and photovoltaic devices is the necessity to provide a reliable alternative to transparent conducting oxide (TCO) like Indium Thin Oxide (ITO). We recently published a study proposing a method to produce transparent conductive electrodes only based on carbon materials. In a first step, we use the Pulsed Laser Deposition (PLD) to produce high performance DLC. Those thin films own very interesting properties in kindship with diamond, like high transparency in the visible range, chemical inertness and biocompatibility. In addition, the DLC is a perfect electrical insulator and presents a relative high opacity in ultra-violet (UV). This particularity has a great interest to perform, in a second step, UV laser annealing over the DLC surface. The aim is to break the existing diamond bindings (sp3 hybridization) on the surface and allow atoms being reorganized in graphitic bindings (sp2 hybridization). We demonstrate that the increase of atomic graphitic bindings leads to a valuable surface conductivity. According to optimized annealing parameters, the surface conductivity reaches values comparable to ITO. We also show that the laser treatments only sparsely affects the DLC transparency. Moreover, this full laser-based process remains compatible with the standard microelectronic technological steps.
关键词： Diamond-Like Carbon (DLC),Graphitization,Pulsed Laser Deposition (PLD),Transparent electrodes,Laser surface annealing
更新于2025-09-12 10:27:22
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Nonlinear Optical Properties of Zinc Oxide Thin Films Produced by Pulsed Laser Deposition
摘要： In this work, the nonlinear optical properties of Zinc Oxide (ZnO) thin films produced on microscope slide glass substrates at room temperature (RT) using Pulsed Laser Deposition (PLD) method has been presented. PLD system consists of a vacuum chamber (pumped by a turbo molecular pump, backed with a rotary pump), rotating sample and substrate holders, optical thickness measurement system, infrared temperature measurement system and a nanosecond laser system. Previously deposition vacuum chamber evacuated down to ~10-8 mbar and deposition was taken place about 1.3×10-1 mbar oxygen background gas pressure value. Morphological properties of thin films were obtained by Atomic Force Microscopy (AFM) that shows homogenous and smooth film structure. Thin films crystallinity were investigated by using X-Ray Diffraction (XRD) method and showed that polycrystalline ZnO structure with the largest peak corresponding to (002) orientation but some films contain Zn with (101) orientation . The thicknesses of the films were deduced from reflectance measurement using a fitting software and crosschecked with profilometer and AFM measurements. The thickness of the films ranged between 10 nm and 220 nm. Linear optical properties were obtained by using UV-VIS Spectrometer. Furthermore, we presented the nonlinear optical properties of the ZnO thin films that were obtained by the z-scan method.
关键词： Z-scan system,Zinc Oxide Thin Film,Nonlinear Optical Properties,Pulsed Laser Deposition
更新于2025-09-12 10:27:22
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The effects of the oxygen content on the photoelectrochemical properties of LaFeO3 perovskite thin films obtained by pulsed laser deposition
摘要： The physical properties of perovskite oxides are strongly influenced by their stoichiometry and one of the key features of these materials is the tunability of their functionality by controlling the interplay between the compositional and structural properties. Here, the effects on the photoelectrochemical (PEC) water splitting properties of ferroelectric LaFeO3 thin films obtained at different oxygen partial pressures during growth are reported in conjunction with the morphological, optical and structural features. The LaFeO3 thin films have been deposited by pulsed laser deposition on Nb:SrTiO3 substrates. The strong dependence of the photocurrent values Jphoto on the growth conditions is revealed by the photoelectrochemical measurements. Strong variations of the lateral coherence lengths L‖ of LaFeO3/Nb:SrTiO3 with the oxygen partial pressure values are noticed from the X-ray diffraction (XRD) analysis. All the films are heteroepitaxial with small tensile strain levels detected in the crystalline structure, but only for a narrow interval of oxygen partial pressures the LFO/STON thin films show high quality crystalline structure with large lateral coherence length L‖ and photoelectrochemical currents.
关键词： oxygen partial pressure,perovskite oxides,photoelectrochemical,pulsed laser deposition,water splitting
更新于2025-09-12 10:27:22
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Pulsed-laser-deposited lead sulfide nanoparticles based decoration of porous silicon layer as an effective passivation treatment for multicrystalline silicon
摘要： We report on the use of pulsed laser deposition (PLD) of PbS nanoparticles (PbS-NPs) on porous silicon layers in order to passivate multicrystalline silicon (mc-Si) substrates intended for solar cells applications. The porous silicon (PS) layer was first obtained through the electrochemical anodization of the mc-Si substrate, and then the PLD technique was used to decorate the PS layer by PbS-NPs at room temperature. By varying the number of laser ablation pulses (NLP) from 50 to 1200, the average size of the PbS-NPs was varied from ~2 nm to ~10 nm. The X-ray diffraction analysis has confirmed the crystalline quality of the PbS-NPs, whereas the transmission electron microscopy observations showed the uniform decoration of the PS by the PbS-NPs. By combining different characterization techniques, we were able to identify NLP = 200 as the optimal decoration condition that leads to the best passivation, in terms of the lowest surface reflectivity (of 15% at 500 nm wavelength), the highest PL intensity of the PS layer (centered around 633 nm) and the longest minority carrier lifetime (as long as ~430 μs versus 40 μs for the bare treated PS layer and 2.2 μs for the untreated bare mc-Si).
关键词： Pulsed laser deposition,Porous silicon,Solar cells,PbS nanoparticles,Surface passivation
更新于2025-09-12 10:27:22
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Laser formation of thin-film memristor structures based on vanadium dioxide
摘要： The thin films of VO2 and the metal-oxide-metal (MOM)-structures of Au/VO2/VO2-x/Au based on them, which are promising for the use in neuromorphic electronic devices, have been obtained by the method of pulsed laser drop-free deposition on the c-sapphire substrates at room temperature. Using the cyclic I-V characteristics, a memristive effect has been revealed in the vertical geometry of the Au/VO2/VO2-x/Au MOM-structures. The x value was varied in the course of their growth by changing the pressure of buffer oxygen from 0.1 to 40 mTorr in the vacuum chamber, which provided the needed conductivity in the depleted injection layer. The dependence of memristive properties on the thickness of the semiconductor layer and concentration of the oxygen vacancies has been established. The oxygen pressure in the PLD method has been determined, at which the volatile behavior of the memristor resistive switching starts to appear at an oxide region thickness of 10/30 nm.
关键词： memristor,VO2,pulsed laser deposition,neuromorphic electronic devices,resistive switching
更新于2025-09-12 10:27:22