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- 实验方案
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Decoupling Effects of Surface Recombination and Barrier Height on p-Si(111) Photovoltage in Semiconductor|Liquid Junctions via Molecular Dipoles and Metal Oxides
摘要： This work provides insight into carrier dynamics in a model photoelectrochemical system comprised of a semiconductor, metal oxide, and metal. To isolate carrier dynamics from catalysis, a common catalytic metal (Pt) is used in concert with an outer-sphere redox couple. Silicon (111) substrates were surface-functionalized with electronegative aryl moieties (p-nitrophenyl and m-dinitrophenyl). A mixed monolayer using p-nitrophenyl/methyl exhibited high surface quality as determined by X-ray photoelectron spectroscopy (low surface SiOx content) and low surface recombination velocity. This substrate also exhibited the expected positive surface dipole, as evidenced by rectifying J?V behavior on p-type substrates, and by positive photovoltage measured by surface photovoltage spectroscopy. Its close molecular relative m-dinitrophenyl exhibited poor electronic surface quality as indicated by high SiOx coverage and high surface recombination velocities (S > 3000 cm s?1). Photoelectrochemical J?V measurements of p-type Si-functionalized surfaces in contact with a high concentration (50 mM) of methyl viologen (MV2+) in aqueous media revealed VOC values that are correlated with the measured barrier heights. In contrast, low-concentration (1.5 mM) MV2+ experiments revealed significant contributions from surface recombination. Next, the electronic and (photo)electrochemical properties were studied as a function of ALD metal oxide deposition (TiO2, Al2O3) and Pt deposition. For the m-dinitrophenyl substrate, ALD deposition of both TiO2 and Al2O3 (150 °C, amorphous) decreased the surface recombination velocity. Surprisingly, this TiO2 deposition resulted in negative shifts in VOC for all surfaces (possibly ALD-TiO2 defect band effects). However, Pt deposition recovered the efficiencies beyond those lost in TiO2 deposition, affording the most positive VOC values for each substrate. Overall, this work demonstrates that (1) when carrier collection is kinetically fast, p-Si(111)?R devices are limited by thermal emission of carriers over the barrier, rather than by surface recombination. And (2) although TiO2 |Pt improves the PEC performance of all substrates, the beneficial effects of the underlying (positive) surface dipole are still realized. Lastly (3) Pt deposition is demonstrated to provide beneficial charge separation effects beyond enhancing catalytic rates.
关键词： solar fuels,interfacial dipole,atomic layer deposition (ALD),surface functionalization,band-edge modulation,photoelectrochemistry
更新于2025-09-23 15:22:29
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Silicon-compatible fabrication of inverse woodpile photonic crystals with a complete band gap
摘要： Three-dimensional (3D) photonic crystals can provide access to very interesting and unique properties for ultimate control and manipulation of photons, not possible otherwise. However, widespread implementation of such photonic crystals remains elusive because the fabrication technology available today has either silicon (Si) incompatibility, poor scalability, a large number of undesired defects, challenging or impossible placement of intentional defects, or has advanced non-standard process steps available only in a few laboratories. In this work, a new methodology of fabricating 3D photonic crystals free of unintentional defects is developed. This methodology is 'truly' Si-compatible and uses techniques available in any standard fabrication facility. A broadband omnidirectional reflector on Si is demonstrated using the same method. Introduction of intentional defect sites for fabrication of 3D waveguides and optical cavities is also discussed.
关键词： Photonic Crystal,Woodpile,Broadband reflector,Band gap,Empty-space-in-Silicon
更新于2025-09-23 15:22:29
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Mimicking a hybrid-optomechanical system using an intrinsic quadratic coupling in conventional optomechanical system
摘要： We consider an optical and mechanical mode interacting through both linear and quadratic dispersive couplings in a general cavity-optomechanical set-up. The parity and strength of an intrinsic quadratic optomechanical coupling (QOC) provides an opportunity to control the optomechanical (OM) interaction. We quantify this interaction by studying normal-mode splitting (NMS) as a function of the QOC's strength. The proposed scheme exhibits NMS features equivalent to a hybrid-OM system containing either an optical parametric amplifier or a Kerr medium. Such a system in reality could offer an alternative platform for devising state-of-art quantum devices with requiring no extra degrees-of-freedom as in hybrid-OM systems.
关键词： Cavity-optomechanics,quadratic optomechanical coupling,normal-mode splitting,resolved side-band regime
更新于2025-09-23 15:22:29
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A novel proposal for all-optical compact and fast XOR/XNOR gate based on photonic crystal
摘要： In this paper, we aim to design an all-optical device, which can perform XOR and XNOR functions in a single structure. The proposed structure will be realized by cascading two nonlinear resonant rings. The functionality of the proposed structure is based on controlling the optical behaviour of optical rings via optical intensity. The final structure has one bias and two input control ports, along with two output ports. One port acts as an XOR and the other acts as an XNOR gate. The maximum delay times for the XOR and XNOR gates are 1.5 and 2.5 ps, respectively. Therefore, the working bit rates for the XOR and XNOR gates are 666 and 400 Gbit/s, respectively.
关键词： band gap,Photonic crystal,XOR/XNOR gate,Kerr effect
更新于2025-09-23 15:22:29
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A 12.8-Gb/s Daisy Chain-Based Downlink I/F Employing Spectrally Compressed Multi-Band Multiplexing for High-Bandwidth, Large-Capacity Storage Systems
摘要： Toward the aim of realizing high-bandwidth, large-capacity nand flash memory-based storage systems, this paper presents a novel daisy-chain downlink interface (I/F) between a controller and a large number of nand packages. The daisy-chain I/F employs a tapered-bandwidth architecture with bridge-by-bridge data extraction based on a proposed spectrally compressed multi-band multiplexing (SCM2) technique to achieve low power consumption. By using the proposed downlink I/F, a nand controller can handle 32 low-cost nand packages while achieving 12.8-Gb/s throughput using two data wires. The fabricated prototype downlink I/F achieved a bit error rate (BER) of 10^-12 with power consumption of 252.1 mW for the transmitter and 375.7 mW for all four receivers together.
关键词： large capacity storage,inter-symbol interference (ISI),daisy chain,Toggle double data rate (DDR),multi-band multiplexing,inter-channel interference (ICI),high-speed I/F,Bridge interface (I/F),high bandwidth,NAND flash memory,multi-drop bus
更新于2025-09-23 15:22:29
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Crystalline topological Dirac semimetal phase in rutile structure
摘要： Based on first-principles calculations and symmetry analysis, we propose that a transition-metal rutile oxide, in particular β-PtO2, can host a three-dimensional topological Dirac semimetal phase. We find that β-PtO2 possesses an inner nodal chain structure when spin-orbit coupling is neglected. Incorporating spin-orbit coupling gaps the nodal chain while preserving a single pair of three-dimensional Dirac points protected by a screw rotation symmetry. These Dirac points are created by a band inversion of two d bands, which is a realization of a Dirac semimetal phase in a correlated electron system. Moreover, a mirror plane in the momentum space carries a nontrivial mirror Chern number nM = -2, which distinguishes β-PtO2 from the Dirac semimetals known so far, such as Na3Bi and Cd3As2. If we apply a perturbation that breaks the rotation symmetry and preserves the mirror symmetry, the Dirac points are gapped, and the system becomes a topological crystalline insulator.
关键词： PtO2,band inversion,symmetry analysis,rutile structure,topological Dirac semimetal,mirror Chern number
更新于2025-09-23 15:22:29
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A D-band Multiplier-based OOK Transceiver with Supplementary Transistor Modeling in 65-nm Bulk CMOS Technology
摘要： A D-band on-off keying (OOK) transceiver chipset is fabricated in a 65-nm bulk CMOS technology as a low-cost and highly-integrative solution to short-distance wireless connectivity. Supplementary transistor modeling is performed for accurate circuit design at mm-wave frequencies. To overcome low transistor fmax and reduce DC power consumption, the transmitter employs a frequency-multiplier-based architecture with no power amplifier. The receiver adopts a non-coherent architecture consisting of a DC-coupled three-stage differential amplifier and an envelope detector. The OOK transmitter exhibits a measured output power of -9.8 dBm and on-off level difference of 13.2 dB at 134.1 GHz. The receiver shows a measured average responsivity of 4.1 kV/W and a noise equivalent power of 211.4 pW/Hz1/2 over all D-band frequencies. The DC power consumption of the transmitter and receiver are 76 mW and 32.5 mW, respectively. The transceiver is tested in both on-chip loopback and air-channel configurations, and demonstrates data transmission up to 10 Gbps and 2 Gbps at a distance of 0.03 m, respectively.
关键词： transceiver,transistor modeling,D-band,wireless communication,low-cost bulk CMOS,OOK
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Advanced Technologies for Communications (ATC) - Ho Chi Minh City, Vietnam (2018.10.18-2018.10.20)] 2018 International Conference on Advanced Technologies for Communications (ATC) - Compact Diversity Multi-band Antennas Using for Low Power Communication Standards
摘要： In this paper, two PIFA multi-band antennas are presented. They are placed at two opposite sides of FR4 PCB. First antenna operates at the frequencies of 0.868 MHz, 1.57 GHz and 2.4 GHz, meanwhile another has the resonant frequencies of 1.57 GHz and 2.4 GHz. The obtained bandwidths cover BLE, GPS and LoRa that are the low power wireless communication standard. Thanks to these specifications, the proposed antenna can be used for the small tracking devices. With the dimension of 0.04λ x 0.07λ (λ is the wavelength at frequency of 0.868 MHz), the antennas provide the radiation efficiency higher than -5 dB for using in LoRa, GPS and BLE. The proposed antennas are simulated and optimized by using HFSS software.
关键词： tracker,LoRa,IoT,multi-band antenna,BLE,GPS
更新于2025-09-23 15:22:29
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Dual-Band High Selective Frequency Selective Surface Design and Analysis
摘要： In this paper, a second-order, dual-band, band-pass frequency selective surface (FSS) with high selectivity is presented by cascading three-layers of periodic metallic arrays. The unit cell in both two exterior layers is composed of gridded-double square loops (G-DSLs) while the element in the middle layer is consisting of wire grid. The three layers are separated by two thin F4B-2 substrates with dielectric constant of 2.65 + 0.02i. The proposed FSS can provide multi-transmission poles and multi-transmission zeros. There are two transmission poles in each pass-band. The two pass-bands are separated by two transmission zeros. On the upper side of the second pass-band, other two transmission zeros are generated also. These transmission zeros lead to a wide out of band rejection and a fast fall off response on both sides of each pass-band. The simulation is implemented using full wave electromagnetic simulator CST Microwave Studio, the central frequencies of the two pass-bands are 12.7 and 17.4 GHz. In addition, the designed principle is described using equivalent circuit model (ECM). Furthermore, the prototype of the FSS is fabricated and measured. Both simulated and measured results demonstrated that the proposed FSS has the merits of incident angle stability from 0° to 60° for both TE and TM polarizations.
关键词： filter,frequency selective surface,dual-band
更新于2025-09-23 15:22:29
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A Generalized Spectral Shaping Method for OFDM Signals
摘要： Orthogonal frequency division multiplexing (OFDM) signals with rectangularly windowed pulses exhibit low spectral confinement. Two approaches usually referred to as pulse-shaping and active interference cancellation (AIC) are classically employed to reduce the out-of-band emission (OOBE) without affecting the receiver. This paper proposes a spectral shaping method that generalizes and unifies these two strategies. To this end, the OFDM carriers are shaped with novel pulses, referred to as generalized pulses, that consist of the ones used in conventional OFDM systems plus a series of cancellation terms aimed at reducing the OOBE of the former. Hence, each generalized pulse embeds all the terms required to reduce its spectrum in the desired bands. This leads to a data-independent optimization problem that notably simplifies the implementation complexity and allows the analytical calculation of the resulting power spectral density (PSD), which in most methods found in the literature can only be estimated by means of simulations. As an example of its performance, the proposed technique allows complying with the stringent PSD mask imposed by the EN 50561-1 with a data carrier loss lower than 4%. By contrasts, 28% of the data carriers have to be nulled when pulse-shaping is employed in this scenario.
关键词： out-of-band emission,pulse-shaping,sidelobes suppression,OFDM,cancellation carriers
更新于2025-09-23 15:22:29