Thin Solid Films最新文献

The increasing demand for microelectronics has significantly driven the advancement of thin film energy storage devices, specifically lithium-ion batteries. In this current work, binder-free lithium cobalt oxide (LCO) has been synthesized by Radio Frequency (RF) magnetron sputtering on aluminium foil substrate in an argon atmosphere. The investigation focused on optimizing the cathode on aluminium foil by varying parameters, such as RF source power, working pressure, and temperature of the substrate. The deposited layers were analyzed for their structural and surface properties to confirm the formation of LCO. The surface of LCO obtained from this binder-free approach helps us create an excellent interface between cathode-electrolyte with a low contact angle (18.1°). An electrochemical analysis of the optimized sample (480 nm thick) was carried out by using 1 M lithium hexa-fluoro-phosphate. The initial charge capacity in the 2 − 4.2 V voltage range was obtained to be 624 mAh/cm³ at the C-rate of 0.05C, which is closer to the theoretical capacity (690 mAh/cm³). Signifying, over 90 % of total lithium is contributed during the charge storage mechanism. As a result, it can be interpreted that the binder-free sputtering technology can be implemented to fabricate efficient electrodes for lithium-ion batteries.

Niobium (Nb) thin films were deposited on a Si substrate using magnetron sputtering system by varying the deposition pressure. The effect of deposition pressure on the microstructure, residual stresses, and electrical properties was investigated by systematically varying the deposition pressure from 0.15 to 0.60 Pa. The Nb thin films were characterized using hard x-ray reflectivity, grazing incidence x-ray diffraction, four point probe method, and atomic force microscopy. The films grown at lower deposition pressures had smooth surfaces and more compact structures, which are advantageous for lowering electrical resistance but had higher compressive stress. On the other hand, the films grown at higher deposition pressures had columnar type growth with less dense structures, which leads to increase in electrical resistance. However the nature of stresses transform from compressive to tensile. Hard X-ray reflectivity performed on Nb films provides direct insight into the growth and the microstructure which were correlated with the mechanical and electrical properties.

The quest for environmentally sustainable alternatives to lead-based dielectric materials in dielectric capacitors has led research to the exploration of options such as silver niobate (AgNbO₃), which has been found to display excellent energy storage properties. Homogeneity and phase-purity of the used thin films are vital for optimal performance of these devices. In this study, a systematic variation of oxygen partial pressure and bias voltage during reactive d.c. magnetron co-sputtering from metallic targets is employed to synthesise AgNbO₃ thin films. Structural and chemical composition of the films are investigated using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, elastic recoil detection analysis, and Rutherford backscattering spectrometry. The findings emphasise the necessity of precise parameter control during deposition to avoid the presence of undesirable secondary phases like Ag and Ag₂Nb₄O₁₁ and to ensure the formation of homogeneous and phase-pure AgNbO₃ thin films. The gained insights demonstrate the potential of reactive d.c. magnetron sputtering for the deposition of lead-free AgNbO₃ thin films, offering pathways for enhanced environmental compatibility of future dielectric capacitors.

Inelastic relaxation in amorphous tin oxide thin films obtained by ion-beam sputtering in an argon atmosphere were studied. The films retain an amorphous structure after annealing at temperatures below 623 K for 30 min and crystallization begins after annealing at 673 K with the formation of two phases, where the SnO₂ phase predominates over the SnO phase. Annealing at 723 K for 30 min leads to a partial transition of the SnO crystalline phase to the SnO₂ phase.

The temperature dependence of internal friction revealed maxima at 585 K and 603 K, identified as β - relaxation maxima, as well as at 690 K, identified as α - relaxation maximum. It is assumed that the β - relaxation maxima at 585 K and 603 K are associated with local hopps of oxygen atoms within the defect structure of SnO₂ and with local hopps of tin atoms within the defect structure of SnO, respectively. The exponential increase in internal friction up to a temperature of 690 K in the α - relaxation region is associated with the diffusion of nonequilibrium vacancy-like defects of the amorphous structure below the glass transition temperature and equilibrium ones above the glass transition temperature. Estimates of the migration energy and formation energy of vacancy-like defects in amorphous tin oxide were made.

Elemental doping has been proven effective in improving the flux pinning of yttrium barium copper oxide (YBa₂Cu₃O_7−δ, YBCO) nanocomposite thin films. In the present work, we increased the number of doping elements to five to investigate the flux pinning effect of YBCO. The Zr-doped, Zr, Hf and Sn co-doped, Zr, Hf, Sn and Ta co-doped, and Zr, Hf, Sn, Ta and Mn co-doped YBCO films deposited on LaMnO₃/MgO/Y₂O₃/Al₂O₃/ Hastelloy substrate were systematically studied. The samples were prepared by low-fluorine metal-organic deposition method, with a total dopant of 8 mol%. All films exhibit good c-axis growth and the multi-doping helps refining the surface particles, resulting in a smoother surface. The in-field properties of the films increase with the increase of co-doped element numbers, especially at a low temperature of 30 K. The pinning force density (F_p) and critical current density (J_c) are significantly improved by five-element Zr, Hf, Sn, Ta and Mn co-doped, which is about 3 times and 1.6 times higher, respectively, than that of the undoped film at 30 K and 1 T.

Heterostructures of the perovskite Pr_0.7Ca_0.3MnO₃ (PCMO) and a tunnel oxide such as AlO_x are highly interesting memristive devices for emulating synaptic properties in neuromorphic circuits. Future chip generations with these memristive elements requires PLD systems which enables PCMO growth on a full wafer. To address the issue of plume broadening in this study, a slit system was used to localize the deposition region, thereby eliminating the need for excessive scanning. This study investigates the effect of the slit system and process gas pressure on plume broadening. This investigation has been used to parameterize a simulation software to assess the effectiveness of different movement speeds and to develop strategies for homogeneous deposition, adjustable to a chosen film thickness in the order of twenty nanometers. We used these strategies to fabricate area dependent switching memory cells on a standard 4″ Si wafer using the material combination of Pr_0.7Ca_0.3MnO₃ and AlO_x. The influence of the aluminum oxide thickness on the switching shows that the IV loop starts to exhibit a hysteresis for AlO_x thicknesses ≥ 3 nm. An increase in AlO_x thickness leads to an increase in resistance and capacitive charging. An additional thermal treatment reduces the resistance and the switching voltage and increases the ratio between low resistive and high resistive state. Devices without thermal treatment of the PCMO are compatible for back end of line processing of standard CMOS technology.

Undoped and lanthanum (La)-doped copper oxide (CuO) thin films were prepared by the nebulizer spray pyrolysis technique. The X-ray diffraction analysis revealed that the effective doping of lanthanum does not alter the monoclinic crystalline structure of copper oxide thin films. Raman spectra confirmed the crystalline quality of undoped and La-incorporated CuO films. From, scanning electron micrograph images, the La-doped CuO films exhibit spherical particles. Energy dispersive X-ray analysis confirmed the existence of copper, lanthanum and oxygen elements. The doping of La-substituted CuO films showed a minimum bandgap when compared to undoped CuO film. The oxidation states of Cu 2p, La 3d and O 1s elements were observed. The electrical resistivity of the films was considerably decreased due to the doping of La ions in CuO matrix. The photoluminescence spectra show that the doping of La ions increases the defect states and shows increased intensity. The time resolved photoluminescence analysis revealed that an extended carrier lifetime was observed for the La-doped films. The La-doped CuO sensors achieved a superior gas sensing performance at room temperature and exhibited quick response and recovery times, suggesting that the sensor has the potential for the detection of harmful volatile gases in real-world applications. The photoconductive investigation revealed that the La-doped CuO films exhibited higher charge-transporting properties and increased light-harvesting ability. This study sheds light on designing gas sensors working under ambient conditions and photosensors for optoelectronic devices.

This research presents a sensitive resistive ethanol gas sensor based on reduced graphene oxide (rGO)-functionalized Zinc oxide nanoflowers (ZnO NFs). Upon completion of synthesis, the resulting nanostructures were cast onto the photolithographed silver interdigitated electrodes positioned on an Al₂O₃ substrate. The graphene oxide (GO) with a low oxidation degree was synthesized using a Hummer's method. In the pursuit of optimizing sensing performance, rGO-functionalized ZnO NFs were synthesized through a one-pot hydrothermal process, utilizing different initial quantities of GO (0 mg, 2 mg, 8 mg, and 12 mg). According to the gas sensing measurements, the fabricated sensor with 8 mg initial GO showed the highest response to ethanol at 250 °C. The results show that the GO addition reduced the optimal working temperature of the pure ZnO NFs from 350 °C to 250 °C. The sensor exhibited a good selectivity, repeatability, and high long-term stability. Enhanced ethanol sensing response of the optimized gas sensor was related to the formation of p-n heterojunction between p-type rGO (formed during hydrothermal process at 200 °C) and n-type ZnO and the presence of the optimal amount of rGO on the surface of NFs. The results obtained in this investigation stress the significance of pinpointing the optimal quantity of GO for producing rGO-ZnO nanoflowers with the highest possible sensitivity to ethanol gas.

In this paper, an effective P⁺ emitter passivation scheme was proposed by continuously optimizing the passivation layer on the front surface of N-type tunnel oxide passivated contact (TOPCon) solar cells, that was using SiO_x/AlO_x/SiN_x tri-layer passivation stack. The SiO_x/AlO_x/SiN_x stack combined the benefits of the chemical passivation effect of SiO_x and the field-effect passivation of SiO_x/AlO_x stack, resulting in high-quality passivation for boron-doped emitter. Three different passivation schemes of SiN_x, AlO_x/SiN_x and SiO_x/AlO_x/SiN_x were respectively prepared on the front surface of N-type TOPCon solar cells. It was revealed that the cells with SiO_x/AlO_x/SiN_x stack had a superior conversion efficiency, while the SiO_x thickness significantly influenced the surface passivation. Through optimization of SiO_x thickness in the SiO_x/AlO_x/SiN_x stack, the optimal deposition period for SiO_x was 4 cycles by the plasma-enhanced atomic layer deposition (PEALD) process. The N-type TOPCon solar cells with SiO_x/AlO_x/SiN_x stack on the front surface exhibited the highest performances with a conversion efficiency of 24.88 % when the deposition period of SiO_x was 4 cycles. Compared with the baseline processes, the efficiency was increased by 0.11 %_abs..

A tungsten coating was formed by the in situ reaction of tungsten trioxide formed by the thermal decomposition of ammonium metatungstate in a molten salt (NaCl+BaCl₂) environment with carbon atoms on the surface of diamond. Meanwhile, diamond/copper composites were prepared using the prepared tungsten-coated diamonds. The morphology and composition of the coatings and diamond/copper composites were observed using scanning electron microscopy, transmission electron microscopy, and energy-dispersive spectroscopy. The results revealed that the originally smooth diamond surface was uniformly covered by a tungsten coating after low-temperature salt bath treatment at 1050 °C, a temperature 50–100 °C lower than that of traditional methods. Compared to the directly added tungsten trioxide, the tungsten trioxide produced by the thermal decomposition of ammonium metatungstate was more active, and the coating was more uniform. The bending strength and thermal conductivity of tungsten-coated diamond/copper composites were 280.6 MPa and 516 W/(m·k), respectively, which were significantly higher than those of uncoated diamond/copper composites (128.6 MPa and 168 W/m·K). This indirectly confirms that the diamond surface coating can improve the interfacial bonding performance between diamond and copper.