Electronic Materials Letters最新文献

Efficient heat energy management during operation remains a critical challenge in Phase Change Memory (PCM) devices. Reducing the thermal conductivity of electrodes has emerged as a promising strategy to address this issue. Amorphous carbon (a-C) thin films present an attractive option for PCM electrodes due to their intrinsically low thermal conductivity and tunable electrical properties. This study focuses on the development of a-C thin films with optimized electrical and thermal characteristics by controlling the sputtering pressure and conducting post-annealing treatments. Various analytical techniques, including X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and Raman spectroscopy, were employed to investigate the microstructure and composition of the a-C thin films. The results demonstrate that the optimal condition for achieving improved electrical and thermal properties is at the lowest sputtering pressure (2.5 mTorr), which is attributed to the reduced impurity content (specifically oxygen and hydrogen) and denser film structure. Furthermore, post-annealing treatment at 400 °C for 30 min resulted in further improvements in thermal and electrical properties due to the formation of sp² clusters and the reduction of impurities within the film. Consequently, the post-annealed a-C thin film exhibited an outstanding low thermal conductivity of 1.34 W m⁻¹ K⁻¹ and an adequate electrical resistivity of 0.02 Ω cm. The findings of this work provide valuable insights into the underlying mechanisms governing the electrical and thermal properties of a-C thin films, paving the way for the development of energy-efficient PCM devices.

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We report the effect of deposition temperature, spanning from 30 °C to 200 °C, on the electrical properties of solid-phase crystallized Ge thin films on SiO₂/Si substrates. Our findings revealed three distinct ranges of deposition temperature, each exhibiting unique electrical properties. The initial thin films were amorphous with low density in the first range (below 100 °C), amorphous with high density in the second range (between 100 °C and 160 °C), and crystalline with high density in the third range (above 160 °C). In the first and second ranges, an increase in deposition temperature led to a fivefold increase in Hall mobility. This was attributed to the enlarged grain size and reduced energy barrier at grain boundaries possibly owing to the reduced concentration of oxygen impurities. Grain boundary scattering dominated carrier transport in the first range, while diminished energy barrier in the second range effectively mitigated grain boundary scattering. In the third range, an increase in deposition temperature resulted in a decrease in the Hall mobility. This may be linked to the reduced grain size. These results demonstrate the profound impact of deposition temperature on tailoring the electrical properties of polycrystalline Ge thin films, with potential implications for semiconductor processing.

Smart windows are significant for their energy-saving function and visual comfort in our daily lives. This review focuses on the latest advancements in reversible metal electrodeposition (RME) smart window technology, examining related issues primarily in terms of long-term operation, high-contrast, and color neutrality in the privacy state. The electrolyte condition is crucial as it significantly impacts factors like nucleation and growth, Faradaic efficiency of optical cycling, bistability, color neutrality, and repeatability. Overcoming these bottlenecks requires designing an appropriate combination of metal ions and additives in the electrolyte. Although aqueous electrolytes have been predominantly used due to their cost-effectiveness, their narrow electrochemical window has raised concerns for real applications. This limitation would lead to the generation of hydrogen or oxygen gases, potentially damaging smart windows. Recent developments have considered non-aqueous electrolytes as a solution, offering a wider electrochemical window, broader operational temperature ranges, and long-term electrolyte stability. These could be key to overcoming the current challenges in smart windows. This review summarizes recent developments in RME smart windows, addressing their current characteristics, improvements, and limitations to provide insights into future pathways for reversible metal electrodeposition-based smart window development.

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Graphene, a promising carbon nanomaterial, has garnered significant attention owing to its chemical stability, exceptional mechanical properties, and remarkable electrical conductivity and is being used in various electrical engineering applications ranging from solar cells to touch screens. The inherent mechanical strength and electric charge capacity of graphene enable efficient designs of diaphragms used in electrostatic loudspeakers, specifically within the high-frequency domain. This study incorporated single-layer and multi-layer graphene sheets, synthesized via chemical vapor deposition, as electrically charged diaphragms in electrostatic loudspeakers paired with an indium tin oxide film electrode to produce Coulomb force. Subsequently, the sound pressure levels of these distinct graphene- based electrostatic loudspeakers were determined through frequency response measurements. Based on our findings, we propose an optimal graphene film configuration for future electrostatic loudspeaker applications.

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In this paper, we studied the alcohol-sensing properties of CoMn₂O₄ nanoparticles for the first time. The CoMn₂O₄ nanoparticles were prepared via a simple microwave-assisted colloidal method using cobalt nitrate, manganese nitrate, dioctyl sulfosuccinate sodium salt, and ethylene glycol as a solvent. Various techniques were used to characterize the structural, morphological, and optical properties of CoMn₂O₄. The crystal structure of CoMn₂O₄ was found after calcination at a temperature of 400 °C. The Raman spectrum showed seven vibrational bands, while the optical absorption spectrum showed three bands, confirming the spinel CoMn₂O₄. Morphological analysis revealed that the porous microstructure of CoMn₂O₄ was composed of nanoparticles with a size distribution of 16 to 58 nm. Gas sensors were fabricated with the CoMn₂O₄ powders calcined at 400 °C using the brush-coating method, and experimental results showed that CoMn₂O₄ nanoparticles were more sensitive to n-butanol than isopropanol and ethanol at an operating temperature of 185 °C. The CoMn₂O₄ sensor showed a response of 6.6 at 50 ppm n-butanol with good stability, reproducibility, and repeatability. The present article provides a new sensing material that could be used as an n-butanol sensor with significant benefits for human health.

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