- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Effect of Macro-scale Mechanical Stress of Silicon Wafer on Room Temperature Photoluminescence Signals
摘要： Mechanical stress was applied to single side polished and double side polished Si wafers in polypropylene wafer containers for different localized stress levels and durations. Room temperature photoluminescence (RTPL) spectra from Si wafers were measured before and after applying localized mechanical stress. Significant changes (up to 26% increase) in RTPL intensity were measured from areas under different stress levels even 1 year after the fixtures for mechanical stress generation were removed. Significant effects of localized mechanical stress on RTPL intensity variations were measured up to 49 days after the fixture removal. Nearly fully relaxed RTPL signatures for localized mechanical stress were measured 450 days after the fixture removal. RTPL intensity is found to be very sensitive to the externally applied macro-scale mechanical stress of Si wafers and residual (or memorized) internal stress even after removal of fixtures for external mechanical stress generation.
关键词： Silicon,room temperature photoluminescence,stress relaxation,mechanical stress
更新于2025-09-23 15:23:52
-
High room-temperature pyroelectric property in lead-free BNT-BZT ferroelectric ceramics for thermal energy harvesting
摘要： Pyroelectrics are attracting increasing attention because they enable pyroelectric generators to extract energy from low-gradient-temperature heat for portable electronic devices. High pyroelectric coefficient around room temperature is essential for high-performance energy harvesters, which, unfortunately, is only commonly achieved in lead-based ferroelectrics. Herein we report a high room temperature pyroelectric response of 27.2 × 10-4 C m-2 K-1 in 0.94(Bi0.5Na0.5)TiO3-0.06Ba(Ti0.75Zr0.25)O3 lead-free ceramics by modulating the Zr4+/Ti4+ ratio to tune the ferroelectric-relaxor antiferroelectric-like phase transition point to around ambient temperature, whose pyroelectric response is one order of magnitude higher than that of the sample without Zr and even comparable to those of lead-containing pyroelectrics. The theoretical analysis revealed that introduced Zr4+ could incorporate into the TiO6 octahedral lattices and break the long-range translational symmetry of BaTiO3 lattices, resulting in the reduction of B-site ion displacement activation energy and transition point of ferroelectric-relaxor antiferroelectric-like phase, giving rise to a pronounced room-temperature pyroelectric effect in BNT-BZT.
关键词： BNT-BZT ceramics,Energy harvesting,Room temperature pyroelectric property,Phase transition
更新于2025-09-23 15:23:52
-
Layer-by-layer self-assembly of polyaniline nanofibers/TiO2 nanotubes heterojunction thin film for ammonia detection at room temperature
摘要： In this paper, for the first time, polyaniline nanofibers/TiO2 nanotubes (PANI/TiO2) heterojunction thin film has been prepared on Pt interdigital electrodes by layer-by-layer self-assembly method and applied in room temperature NH3 detection. It is found that the optimal self-assembly layer number is three (PANI/TiO2-3) compared to one layer (PANI/TiO2-1) and five layers (PANI/TiO2-5). The PANI/TiO2-3 thin film sensor possesses superior response characteristics compared with our other PANI based sensors, including higher response value (336%@5 ppm NH3), acceptable response/recovery time (110 s/1086 s@5 ppm NH3), low detection limit (0.5 ppm), and remarkable selectivity. The enhanced gas sensing performances could be ascribed to the tremendous variation of the carrier concentration caused by the p-n junctions as well as the increased specific surface area and pore volume. This work not only offers a superb strategy to fabricate heterojunction thin film but also accelerates the development of room-temperature operable NH3 sensors.
关键词： Ammonia detection,Layer-by-layer self-assembly,Polyaniline/TiO2 heterojunction,Thin film,Room temperature operation
更新于2025-09-23 15:23:52
-
Sol-gel assisted nano-structured SnO<sub>2</sub> sensor for low concentration ammonia detection at room temperature
摘要： Sol-gel assisted nano-structured SnO2 sensor for low concentration ammonia detection at room temperature. Upon exposure to 500 ppb and 1 ppm of NH3, sensor manifests appreciable response ~ 28 % and ~ 31.5 %, respectively. High response of the sensor at RT is attributed due to porous nanograins (with average particle size ~ 50 nm) based SnO2 thin film layer. Nanograins structure is obtained due to addition of glycerine in the sol solution, which also leads to porosity enhancement of the sensing layer. Good reproducibility and appreciable immunity to drift behavior are other attributes of the fabricated device. High response and good selectivity towards ammonia are observed with very fast response and recovery time at RT, for extreme low concentrations level ~ 55 % RH for concentration range 500 ppb-500 ppm. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electron microscopy (SEM) results are used to study the structural, chemical composition, topography and morphological characteristics of the prepared SnO2 thin film, respectively.
关键词： Sol-gel,Room temperature,Ammonia sensor,Metal oxides,% Response,Nanostructured
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE CPMT Symposium Japan (ICSJ) - Kyoto, Japan (2018.11.19-2018.11.21)] 2018 IEEE CPMT Symposium Japan (ICSJ) - Surface analysis of argon and oxygen plasma-treated gold for room temperature wafer scale gold-gold bonding
摘要： The effects of Ar and O2 plasma treatments on Au surface properties were investigated in terms of room-temperature wafer-scale Au-Au bonding. X-ray photoelectron spectroscopy analysis indicated that O2 plasma treatment formed gold oxide (Au2O3) on Au surfaces, and bonded samples treated by O2 plasma showed weak bonding strength (0.14-0.16 J/m2). It seems that Au2O3 impeded Au-Au bonding. On the other hand, strong Au-Au bonding was obtained by using Ar plasma treatment, and bonded samples were fractured at the bulk wafers during the blade test.
关键词： O2 plasma,Room-temperature bonding,Au-Au bonding,Ar plasma
更新于2025-09-23 15:22:29
-
Hydrogen Gas Sensing Characterizations Based on Nanocrystalline SnO<sub>2</sub> Thin Films Grown on SiO<sub>2</sub>/Si and Al<sub>2</sub>O<sub>3</sub> Substrates
摘要： High-quality nanocrystalline (NC) SnO2 thin films were grown on SiO2/Si and Al2O3 substrates using sol–gel spin coating method. The structural properties, surface morphologies and gas sensing properties of the NC SnO2 were investigated. XRD measurements showed a tetragonal rutile structure and the diffraction peaks for NC SnO2 thin films grown on Al2O3 substrates outperformed those of NC SnO2 films grown on SiO2/Si substrates. The surface morphology of the annealed SnO2 thin films at 500 oC appeared as polycrystalline with uniform nanoparticle distribution. Hydrogen (H2) gas sensing performance of the NC SnO2 was examined for H2 concentrations ranging from 150 ppm to 1000 ppm at different temperatures (room temperature, 75 and 125 oC) for over 50 min. The room temperature sensitivities for H2 gas sensors based on NC SnO2 thin films grown on Al2O3 and SiO2/Si substrates was 2570% and 600%, respectively upon exposure to 1000 ppm of H2 gas. While the sensitivity values at 125 oC increased to 9200% and 1950%, respectively.
关键词： Sensing,Room Temperature,Hydrogen,Nanocrystalline SnO2,Thin Films,Sol-Gel
更新于2025-09-23 15:22:29
-
Room temperature multi-phonon upconversion photoluminescence in monolayer semiconductor WS2
摘要： Photon upconversion is an anti-Stokes process in which an absorption of a photon leads to a reemission of a photon at an energy higher than the excitation energy. The upconversion photoemission has been already demonstrated in rare earth atoms in glasses, semiconductor quantum wells, nanobelts, carbon nanotubes and atomically thin semiconductors. Here, we demonstrate a room temperature upconversion photoluminescence process in a monolayer semiconductor WS2, with energy gain up to 150 meV. We attribute this process to transitions involving trions and many phonons and free exciton complexes. These results are very promising for energy harvesting, laser refrigeration and optoelectronics at the nanoscale.
关键词： photoluminescence,monolayer semiconductor,phonons,energy gain,room temperature,WS2,excitons,trions,upconversion
更新于2025-09-23 15:22:29
-
High-performance Raman quantum memory with optimal control in room temperature atoms
摘要： Quantum memories are essential for quantum information processing. Techniques have been developed for quantum memory based on atomic ensembles. The atomic memories through optical resonance usually suffer from the narrow-band limitation. The far off-resonant Raman process is a promising candidate for atomic memories due to broad bandwidths and high speeds. However, to date, the low memory efficiency remains an unsolved bottleneck. Here, we demonstrate a high-performance atomic Raman memory in 87Rb vapour with the development of an optimal control technique. A memory efficiency of above 82.0% for 6 ns~20 ns optical pulses is achieved. In particular, an unconditional fidelity of up to 98.0%, significantly exceeding the no-cloning limit, is obtained with the tomography reconstruction for a single-photon level coherent input. Our work marks an important advance of atomic memory towards practical applications in quantum information processing.
关键词： room temperature atoms,broadband,optimal control,Raman quantum memory,high efficiency,high fidelity
更新于2025-09-23 15:22:29
-
Magnetic-field-dependent quantum emission in hexagonal boron nitride at room temperature
摘要： Optically addressable spins associated with defects in wide-bandgap semiconductors are versatile platforms for quantum information processing and nanoscale sensing, where spin-dependent inter-system crossing transitions facilitate optical spin initialization and readout. Recently, the van der Waals material hexagonal boron nitride (h-BN) has emerged as a robust host for quantum emitters, promising efficient photon extraction and atom-scale engineering, but observations of spin-related effects have remained thus far elusive. Here, we report room-temperature observations of strongly anisotropic photoluminescence patterns as a function of applied magnetic field for select quantum emitters in h-BN. Field-dependent variations in the steady-state photoluminescence and photon emission statistics are consistent with a spin-dependent inter-system crossing between triplet and singlet manifolds, indicating that optically-addressable spin defects are present in h-BN.
关键词： photoluminescence,room temperature,quantum emitters,magnetic field,hexagonal boron nitride,spin defects
更新于2025-09-23 15:22:29
-
Controlling the fluorescence and room-temperature phosphorescence behaviour of carbon nanodots with inorganic crystalline nanocomposites
摘要： There is a significant drive to identify alternative materials that exhibit room temperature phosphorescence for technologies including bio-imaging, photodynamic therapy and organic light-emitting diodes. Ideally, these materials should be non-toxic and cheap, and it will be possible to control their photoluminescent properties. This was achieved here by embedding carbon nanodots within crystalline particles of alkaline earth carbonates, sulphates and oxalates. The resultant nanocomposites are luminescent and exhibit a bright, sub-second lifetime afterglow. Importantly, the excited state lifetimes, and steady-state and afterglow colours can all be systematically controlled by varying the cations and anions in the host inorganic phase, due to the influence of the cation size and material density on emissive and non-emissive electronic transitions. This simple strategy provides a flexible route for generating materials with specific, phosphorescent properties and is an exciting alternative to approaches relying on the synthesis of custom-made luminescent organic molecules.
关键词： room temperature phosphorescence,photoluminescence,heavy atom effect,carbon nanodots,nanocomposites
更新于2025-09-23 15:22:29