- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Tellurene Photodetector with High Gain and Wide Bandwidth
摘要： Two-dimensional (2D) semiconductors have been extensively explored as a new class of materials with great potential. In particular, black phosphorus (BP) has been considered to be a strong candidate for applications such as high-performance infrared photodetectors. However, the scalability of BP thin film is still a challenge, and its poor stability in the air has hampered the progress of the commercialization of BP devices. Herein, we report the use of hydrothermal-synthesized and air-stable 2D tellurene nanoflakes for broadband and ultrasensitive photodetection. The tellurene nanoflakes show high hole mobilities up to 458 cm2/V·s at ambient conditions, and the tellurene photodetector presents peak extrinsic responsivity of 383 A/W, 19.2 mA/W, and 18.9 mA/W at 520 nm, 1.55 μm, and 3.39 μm light wavelength, respectively. Due to the photogating effect, high gains up to 1.9 ×103 and 3.15×104 are obtained at 520 nm and 3.39 μm wavelength, respectively. At the communication wavelength of 1.55μm, the tellurene photodetector exhibits an exceptionally high anisotropic behavior, and a large bandwidth of 37 MHz is obtained. The photodetection performance at different wavelength is further supported by the corresponding quantum molecular dynamics (QMD) simulations. Our approach has demonstrated the air-stable tellurene photodetectors that fully cover the short-wave infrared band with ultrafast photoresponse.
关键词： air-stable,two-dimensional (2D),wide bandwidth,tellurene,photodetector,high gain
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Generation of Ultrabroadband Phase-Locked Pulse Pairs in the Ultraviolet by Achromatic SHG
摘要： Two-dimensional electronic spectroscopy (2DES) is a powerful spectroscopic technique for the study of dynamics in coupled multi-chromophore systems, which has been successfully applied in the visible and infrared ranges. Its extension to the UV range (2DUV) is extremely promising for the study of biomolecules but poses several technical challenges: (i) the requirement of phase-locked pulse pairs; (ii) generation of extremely broadband UV pulses; (iii) dispersion management for the UV range. Here we present a setup able to generate ultrabroad phase-locked UV pump pulses with bandwidth from 260 to 310 nm. The UV pump pulse pairs are generated by Achromatic Second Harmonic Generation (ASHG) of a phase-locked, visible pulse pair (Fig. 1(a)). A non-collinear optical parametric amplifier (NOPA) produces 10-μJ, <6-fs-pulses in the 500-640 nm range. Two delayed, phase-locked replicas of the visible pulses are then generated by TWINS [1], a compact ultrastable interferometer consisting of a sequence of β-BBO birefringent wedges that allows varying with extreme accuracy and up to 1 ps the delay between the two replicas. The broadband visible replicas are subsequently chirped in a 45-mm block of SF57 and frequency doubled to the UV range by ASHG [2]. In this scheme, the visible pulse is dispersed by a fused silica (FS) prism and the angular dispersion is converted to a lateral dispersion by a second prism. The resulting collimated beam is focused into a 300-μm β-BBO crystal for SHG. By suitably choosing the prism separation (152 cm) and the focal length (35 mm) we match the propagation direction of each component with its SHG phase-matching angle.
关键词： ultrabroadband UV pulses,UV range,Two-dimensional electronic spectroscopy,Achromatic Second Harmonic Generation,phase-locked pulse pairs
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Excitonic Effects in Single Layer MoS <sub/>2</sub> Probed by Broadband Two-Dimensional Electronic Spectroscopy
摘要： Atomically thin Transition-metal dichalcogenides (TMDs) have come into the spotlight in optoelectronics thanks to their outstanding physical properties. In single-layer (1L) TMDs strong quantum confinement effects cause a weak screening of Coulomb, so that the excitons created by photo-excitation have large binding energy, up to several hundred meVs. While the steady-state properties of TMDCs have been studied in detail by linear optical techniques, the recent application of time-resolved nonlinear spectroscopy (mainly ultrafast pump-probe) has enabled the study of excited-state dynamics on femtosecond timescales opening up questions about the mechanisms of exciton relaxations and exciton-exciton interactions. Among TMDs, the spectrum of 1L MoS2 is characterized by two peaks of excitonic nature in the visible spectral region (1.9 eV and 2.05 eV), the so-called A and B excitons. They arise from optical transitions between the spin?orbit split top valence band and the bottom conduction band, around K and K’. Here we use two-dimensional electronic spectroscopy (2DES) to track the sub-ps excitonic interactions within 1L MoS2. We report 2DES measurements obtained on a chemical vapor deposition grown 1L MoS2 sample, at 77K, using sub 20-fs broadband pulses. Thanks to its unique combination of high temporal and spectral resolution, 2DES provides a series of excitation/detection correlation energy maps at different delays T, simultaneously covering the A and B excitons.
关键词： excitonic effects,MoS2,Transition-metal dichalcogenides,two-dimensional electronic spectroscopy
更新于2025-09-12 10:27:22
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Integrated color photodetectors in 40 nm standard CMOS technology
摘要： For the further integration of receivers in multi-color visible light communication systems, a novel color photodetector (PD) was designed and fabricated by using a 40 nm standard complementary metal oxide semiconductor (CMOS) process without any process modifications. The PD consists of CMOS photodiode and two-dimensional (2D) polysilicon subwavelength grating above the photodiode. The 2D polysilicon grating is controlled in structural parameters to realize color filtering, based on guided-mode resonance, for the first time in a standard CMOS process. Here three kinds of color PDs were designed to respond to the three primary colors. The measured results demonstrate that the color PDs exhibit wavelength selectivity in the visible range (400-700 nm) and the maximum peaks in the spectral response curves of them are at 660 nm (red), 585 nm (green) and 465 nm (blue), respectively. In addition, the added 2D polysilicon grating almost does not reduce the responsivity of the photodiodes.
关键词： two-dimensional polysilicon subwavelength grating,Color photodetector,visible light communication,complementary metal oxide semiconductor (CMOS)
更新于2025-09-12 10:27:22
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Dynamic proportional-fuzzy grip control for?robot arm by two-dimensional vision sensing method
摘要： In this study, a four-degree of freedom (4-DOF) robot arm uses an innovative two-dimensional vision sensing method to grip a moving target on a moving platform. This study utilizes forward and inverse kinematics to establish a dynamic model of the 4-DOF robot arm. A computer as a controller and a single charge-coupled device (CCD) calculates the two-dimensional vision sensing method and sends commands to an Arduino Uno microcontroller to drive the robot arm. According to simulation results of transient and steady states in MATLAB SimMechanics, the response of the dynamic proportional-fuzzy controller is better than the response of proportional–integral–derivative controller. To demonstrate a precise control of the point-contact grip, this study utilizes a ping pong ball as a target on a moving platform. Using the dynamic proportional-fuzzy controller based on the two-dimensional vision sensing method, the 4-DOF robot arm can position, grip, and carry a moving ping pong ball to a designated place in three-dimensional space, which breaks through the previous two-dimensional limitation using a single CCD. This breakthrough can reduce the weight and cost of the robot arm. Therefore, this study aims to utilize the technology to grip moving targets on a moving platform for manpower cost reduction in the industry or agriculture domain in the future.
关键词： dynamic proportional-fuzzy controller,two-dimension limitation using a single CCD,Four-degree of freedom robot arm,forward and inverse kinematics,two-dimensional vision sensing method
更新于2025-09-11 14:15:04
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Electron-hole superfluidity controlled by a periodic potential
摘要： We propose controlling an electron-hole super?uid in semiconductor coupled quantum wells and double layers of a two-dimensional (2D) material by an external periodic ?eld. This can be created either by the gates periodically located and attached to the quantum wells or double layers of the 2D material or by the moiré pattern of two twisted layers. The dependence of the electron-hole pairing order parameter on the temperature, the charge carrier density, and the gate parameters is obtained by minimization of the mean-?eld free energy. The second-order phase transition between super?uid and electron-hole plasma, controlled by the external periodic gate ?eld, is analyzed for different parameters.
关键词： mean-?eld free energy,semiconductor coupled quantum wells,electron-hole super?uid,phase transition,external periodic ?eld,two-dimensional material
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Lviv, Ukraine (2019.7.2-2019.7.6)] 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Surface and Bulk Wave Modes of Two Dimensional Photonic Crystal Waveguide
摘要： Electrodynamical characteristics of the two-dimensional photonic crystal waveguide are considered. Effect of the width of hollow waveguide channel on the dispersion characteristics and spatial distribution of electric field is analyzed. Slow wave localized modes with phase velocity less than speed of light are supported by photonic crystal waveguide and can be used for synchronization with linear electron beams in the terahertz beam-wave systems. Widening of the waveguide hollow channel does not result in significant decrease of the electric field intensity on the axis of waveguide as occur in metallic slow-wave systems.
关键词： spatial harmonics,dispersion characteristics,two-dimensional photonic crystal waveguide,terahertz range,slow wave modes
更新于2025-09-11 14:15:04
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Plasmonic Trimers for Dual-Frequency Surface-Enhanced Two-dimensional Infrared Spectroscopy
摘要： Extension of surface-enhanced two-dimensional infrared spectroscopy (SE-2DIR) to dual-frequency experiments allows to study dynamics and energy transport in thin molecular films by tagging and probing vibrational modes on different sites of the molecule. Measurements of cross-peaks involving transitions largely separated in frequency by SE-2DIR require plasmonic nanostructures with resonant excitations at the corresponding frequencies, where the associated enhanced near-fields spatially overlap and different molecular transitions are simultaneously enhanced in the same molecule. Gold trimer infrared antennas localize enhanced fields within the gap formed by their arms. We exploit the symmetry of trimer antennas to individually tune frequencies of the in-plane plasmonic excitations to match molecular transitions of interest. Dual-frequency SE-2DIR measurements are demonstrated on 4-azidobutyrate-N-hydroxysuccinimide ester with the cross-peaks between the carbonyl and azido stretching vibrational modes, separated by 370 cm-1, and the carbonyl and C-N-C stretching modes, separated by 550 cm-1. Excitation with cross-polarized laser pulses allows to selectively access appropriate plasmon excitations in resonance with the relevant molecular transitions. Our approach, based on the rational plasmon mode engineering, achieves significant enhancement of the cross-peak signals involving largely-separated transition frequencies, which is not possible with single broadband plasmon modes.
关键词： Surface-Enhanced Two-dimensional Infrared Spectroscopy,Dual-frequency,Molecular transitions,Cross-peaks,Gold trimer infrared antennas,Plasmonics,Hybrid Materials,Optical,Magnetic
更新于2025-09-11 14:15:04
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Two-Dimensional Heterojunction Photovoltaic Cells with Low Spontaneous-Radiation Loss and High Efficiency Limit
摘要： This work presents theoretical investigations on the spontaneous-radiation loss of two-dimensional van der Waals heterojunction photovoltaic cells (2D-PVcs) combined with an interference-based light-trapping structure. We find that 2D-PVcs possess much lower spontaneous radiation loss, since the solid angle of the spontaneous radiation is a magnitude smaller than that in traditional PVcs. The efficiency limit of a 2D-PVc can be 10% larger than that of a traditional PVc. Furthermore, we demonstrate that the spontaneous-radiation loss can be further reduced by introducing only a weak light-concentrating system, approaching the efficiency limit of traditional PVcs under perfect focus. In a trapped structure, the smaller the light absorption coefficients of the photovoltaic cells, the higher are the efficiency limits that are achieved. Finally, the spontaneous-radiation loss increases as the battery thickness increases, indicating that the 2D-PVc has the lowest spontaneous emission loss because of its extremely low thickness.
关键词： photovoltaic cells,two-dimensional heterojunction,spontaneous-radiation loss,light-trapping structure,efficiency limit
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Direct Laser Synthesis of Two-Dimensional Transition Metal Dichalcogenides
摘要： The emergence of nanomaterials with their often superior mechanical, electronic and optical properties compared with bulk form demands a robust technology that can synthesize, modify and pattern scalably and cost effectively. This can be fulfilled via laser processing protocols which produce such materials with both high precision and excellent spatial controllability [1]. Direct laser synthesis of nanomaterials such as graphene and nano-structured metal oxides have been explored thoroughly for a wide range of applications [2,3]. However, to date, there are only a few reports associated with the laser processing of two-dimensional transition metal dichalcogenides (2D-TMDCs) [4]. These mainly utilize laser radiation for thinning TMDC films through sublimation down to a single molecular thickness [1]. However, this top-down approach is not practical for large- area and scalable production. In addition, further processing steps such as lithographic patterning are then required for discrete device fabrication. Here we present a novel method for the local synthesis and patterning of two-dimensional MoS2 and WS2 layers. The synthesis of these materials is achieved by spatially selective, visible laser irradiation of suitable precursors coated on the surface of planar substrates under ambient, room temperature conditions. The non- exposed precursor regions are then completely removed in a single step, revealing the synthesised 2D-TMDCs. This method can produce micro-patterned films with lateral dimensions that approach the diffraction limit of the focused laser beam. An example of such laser synthesised MoS2 tracks can be seen in the optical microscopy image of Figure 1(a) where it clearly shows a well-defined micro-pattern without any precursor residue. Using this method, we have achieved local synthesis of of MoS2 and WS2 with thickness down to three molecular layers for MoS2 and monolayer WS2 on various glass and crystalline substrates. The quality and thickness of the resulting films can be tuned by modifying the precursor chemistry and laser parameters. Different microprobe and spectroscopic spectroscopy, photoluminescence spectroscopy (PL) and X-ray photoelectron spectroscopy (XPS) have been used to assess the quality and thickness of the deposited MoS2 and WS2 structures. Finally, we have demonstrated the electronic functionality of our films by fabricating a thin film transistor (TFT). The transfer characteristics (source-drain current vs gate voltage) of such a TFT using a laser-synthesised MoS2 channel is shown in Figure 1(b).
关键词： Two-Dimensional Transition Metal Dichalcogenides,WS2,MoS2,Direct Laser Synthesis,Thin Film Transistor
更新于2025-09-11 14:15:04