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Room Temperature Bonding of Wafers Using Si and Ge Films with Extremely Low Electrical Conductivity
摘要： The technical potential of room temperature bonding of wafers in vacuum using amorphous Si (a-Si) and Ge (a-Ge) films was studied. Transmission electron microscopy images revealed no interface corresponding to the original films surfaces for bonded a–Ge–a–Ge films. Analyses of film structure and the surface free energy at the bonded interface revealed higher bonding potential at the connected a–Ge–a–Ge interface than that of a–Si films. The electrical resistivity of a-Ge films is 0.62 ?m, which is lower than that of a-Si film (4.7 ?m), but 7–8 order higher than that of representative material films used for bonding in vacuum. Our results indicate that room temperature bonding using a–Ge films is useful to bond wafers without any marked influence on the electrical properties of devices on wafer surfaces caused by the electrical conductivity of films used for bonding.
关键词： room temperature bonding,electrical conductivity,amorphous Ge,wafer bonding,amorphous Si
更新于2025-09-09 09:28:46
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Ultralong Organic Phosphorescence in the Solid State: the Case of Triphenylene Cocrystals with Halo- and Dihalo-penta/tetrafluorobenzene
摘要： The polycyclic aromatic hydrocarbon (PAH) triphenylene (TP) has been reacted with halo-pentafluorobenzene (XF5, X = Br, I) and 1,4-dihalo-tetrafluorobenzene (X2F4, X = Br, I) to yield the corresponding cocrystals TP·BrF5, TP·Br2F4, TP·IF5, and TP·I2F4 form I. These materials have been synthesized by dissolving TP into an excess of liquid or molten co-former, and single crystals have been grown via seeding chloroform solutions. They have been fully characterized by a combination of techniques including X-ray diffraction, Raman, and luminescence spectroscopy in the solid state. TP·I2F4 form I was found to undergo a single-crystal to single-crystal (SCSC) polymorphic phase transition induced by temperature (when cooled down to 100K) leading to the new form TP·I2F4 form II, which is transformed back into the first structure when brought again at RT. This behavior was confirmed also by Raman spectroscopy. Upon cocrystallization and as a result of the external heavy atom effect, all crystalline materials exhibited bright room temperature phosphorescence clearly visible by naked eye. The latter was almost exclusive for cocrystal TP·I2F4, whereas for TP·Br2F4 both fluorescence and phosphorescence were detected. In TP·Br2F4, the phosphorescence lifetime was of the order of 200 ms, and with the visual outcome of an orange phosphorescence lasting for a couple of seconds upon ceasing the excitation, that makes this compound classifiable as an Ultralong Organic Phosphorescent (UOP) material. The results evidenced the role of the nature of the heavy atom in governing the phosphorescence output from organic cocrystals.
关键词： Room Temperature Phosphorescence,Triphenylene Cocrystals,Ultralong Organic Phosphorescence,Dihalo-tetrafluorobenzene,Halo-pentafluorobenzene
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - Measuring Thermal Acoustic Radiation with an Optomechanical Antenna
摘要： We optically probe the SiN membrane nanomechanical resonator modes that are strongly coupled to acoustic radiation into the substrate. We use this optomechanical system for temperature metrology by detecting the ballistic transport of thermal excitations from a remote bath.
关键词： Metrology,Temperature Sensors,Optomechanics,Photonics,Thermal Noise,Nanophotonics
更新于2025-09-09 09:28:46
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Gate switching of ultrafast photoluminescence in graphene
摘要： The control of optical properties by electric means is the key to optoelectronic applications. For atomically thin two-dimensional (2D) materials, the natural advantage lies in that the carrier doping could be readily controlled through the electric gating effect, possibly affecting the optical properties. Exploiting this advantage, here we report the gate switching of the ultrafast upconverted photoluminescence from monolayer graphene. The luminescence can be completely switched off by the Pauli-blocking of one-photon interband transition in graphene, with an on/off ratio exceeding 100 times, which is remarkable compared to other 2D semiconductors and 3D bulk counterparts. The chemical potential and pump fluence dependences of the luminescence are nicely described by a two-temperature model, including both the hot carrier dynamics and carrier-optical phonon interaction. This gate switchable and background-free photoluminescence can open up new opportunities for graphene-based ultrafast optoelectronic applications.
关键词： ultrafast photoluminescence,gate switching,hot carriers,graphene,optoelectronics,two-temperature model
更新于2025-09-09 09:28:46
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Piezoelectric-Based Support Transducer Design to Enable High-Performance Bulk Mode Resonators
摘要： An innovative topology to realize high-performance bulk mode devices made up of low-defect material by driving them into resonance using piezoelectric thin-film transduction is proposed and implemented in this paper. Here, the piezoelectric transducer is uniquely positioned at the bulk mode’s support location. To realize the resonators, MEMSCAP Inc.’s PiezoMUMPS platform was utilized. Wine-glass and Lamé bulk mode devices are demonstrated to establish the feasibility of the support transducer drive/sense mechanism. Several drive/sense combinations of the balanced–unbalanced setup were measured. For the differential-in differential-out configuration, reduced feedthrough and enhanced stop-band rejection was observed. As a result, the Wine-glass and Lamé mode resonators having a resonance frequency ( fr ) of 20.943 and 21.15 MHz with a motional resistance (Rm) of 1.68 and 3.88 kΩ and a loaded quality factor ( Ql ) of 9940 and 6840, respectively, operating in vacuum at 0-dBm driving power are demonstrated. Temperature Coefficient of Frequency of ?26.4 and ?25 ppm/K is recorded for Wine-glass and Lamé mode resonators, respectively. To characterize the closed-loop response of the devices, they were connected to a lock-in amplifier with phase-locked loop, and a phase noise of ?122 and ?118 dBc/Hz at 1-kHz offset were measured for Wine-glass and Lamé mode resonators, respectively.
关键词： Bulk mode,wine-glass,transducer,differential-in,piezoelectric,Lamé mode,differential-out,phase noise,temperature coefficient of frequency
更新于2025-09-09 09:28:46
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A review on low-molar-mass carbazole- based derivatives for organic light emitting diodes
摘要： Organic light emitting diodes (OLEDs) have attracted a great deal of attention within academia and industry because of their potential applications in flat panel displays and solid-state lighting technologies. Among all low-molar-mass derivatives under investigation in OLEDs field, carbazole-based materials have been studied at length for their interesting physical properties, including good charge injection and transport, electro-luminescence, improved thermal and morphological stabilities as well as film forming properties. In addition, the relatively high triplet energy level of some substituted carbazoles makes them suitable candidates to design hosts for wide bandgap triplet emitters such as blue dopants. The article is written from structural organic chemist's point of view and is divided in several parts: V-shaped 3(2)-substituted carbazoles and derivatives with 9-carbazolyl rings, star-shaped 3,6(2,7)-substituted carbazoles and branched twin derivatives containing (di)arylcarbazolyl fragments.
关键词： Amorphous material,Ionization potential,Glass transition temperature,Organic light emitting diode,Substituted carbazole,Hole transporting material
更新于2025-09-09 09:28:46
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Light-Assisted Room-Temperature NO2 Sensors Based on Black Sheet-Like NiO
摘要： In this study, we use two-dimensional black flake nickel oxide as the sensitive material which was synthesized by a facile hydrothermal route. The as-synthesized sheet-like NiO possessed a large specific surface area, as verified by BET characterization. The as-prepared NiO nanosheets had strong absorption in the range of 250–800 nm including UV and visible light. Upon exposure to ppb-level NO2, the presented sensors showed significant responses under light illumination at room temperature. In addition, the light wavelength also had a remarkable effect on the sensing performance in terms of sensitivity, response and recovery kinetics. Furthermore, the sensor showed a low humidity dependence.
关键词： NiO,light illumination,room temperature,NO2
更新于2025-09-09 09:28:46
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Analysis and Design of an Effective Light Interference Methane Sensor Based on Three-Dimensional Optical Path Model
摘要： As an important environmental monitoring equipment, the existing methane sensors or the traditional interferometer-based methane detectors have some drawbacks, such as low accuracy, large size, and complex calibration operations. Moreover, the optical path model and analysis method for the light interference methane sensor are not practical. In this paper, an effective light interference methane sensor is proposed based on a three-dimensional optical path model with point light source. Based on this model, the interference optical system is studied to illustrate the cause of the interference fringes. Furthermore, the influencing factors of the light intensity distribution are analyzed and an adjustment method for the interference fringes is proposed, which helps to simplify the assembling and calibrating operations. In order to improve the measurement accuracy, a temperature drift compensation method which includes a mapping table, a steady-state compensator, and a dynamic compensator is proposed. The mapping table is established between the output voltages of photoelectric detector, and the methane concentration, the steady-state compensator, and the dynamic compensator are proposed to eliminate the temperature drift. Finally, an experimental device for the light interference methane sensor is constructed to validate the interference fringe adjustment method and the temperature drift compensation method.
关键词： temperature drift compensation,light interference,methane sensor,three-dimensional optical path model,interference fringes
更新于2025-09-09 09:28:46
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Visible-Light Photocatalyzed Deoxygenation of N-Heterocyclic <i>N</i> -Oxides
摘要： A scalable and operationally simple method is described that allows for the chemoselective deoxygenation of a wide range of N-heterocyclic N-oxides (a total of 36 examples). This visible-light-induced protocol features the use of only commercially available reagents, room-temperature conditions, and unprecedented chemoselective removal of the oxygen atom in a quinoline N-oxide in the presence of a pyridine N-oxide in the same molecule through the judicious selection of a photocatalyst.
关键词： chemoselective,deoxygenation,room-temperature,N-heterocyclic N-oxides,visible-light photocatalysis
更新于2025-09-09 09:28:46
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Thermal Reshaping Dynamics of Gold Nanorods: Influence of Size, Shape, and Local Environment
摘要： The thermal reshaping of gold nanorods in a polymer matrix is an important phenomenon for many potential applications. However, a fundamental understanding of the various mechanisms that govern the nanorod reshaping dynamics is still lacking. Here we provide evidence for a phenomenological model of the gold nanorod shape transformation based on the measurements and detailed analysis of the time-resolved thermal reshaping for a variety of gold nanorods having different geometries (aspect ratio, volume, diameter) in a crosslinked epoxy matrix at application relevant temperatures (120 ? 220 ?C). Our analysis suggests that a) the nanorod reshaping dynamics consist of two temporal regimes that are governed by different phenomena, and b) the ultimate amount of reshaping at a given temperature depends strongly on the initial particle geometry and the mechanical stiffness of its surroundings. At short times the shape transformation is dominated by a curvature-induced surface diffusion process in which the activation energy for diffusion depends on curvature. At long times, however, the surrounding environment plays a key role in slowing the diffusion and stabilizing the nanorod shape. We show that the long time behavior can be well described using a modified surface diffusion model that takes into account the slowing of atomic diffusivity as a result of external forces arising from mechanical constraints. The ability to tune both the final shape and the reshaping dynamics in nanocomposites opens up new possibilities in tailoring the optical properties of these materials.
关键词： Polymer Nanocomposites,Surface Diffusion,Temperature Sensing,Plasmonics,Thermal Reshaping,Gold Nanorods
更新于2025-09-09 09:28:46