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MOVPE of Large-Scale MoS <sub/>2</sub> /WS <sub/>2</sub> , WS <sub/>2</sub> /MoS <sub/>2</sub> , WS <sub/>2</sub> /Graphene and MoS <sub/>2</sub> /Graphene 2D-2D Heterostructures for Optoelectronic Applications
摘要： Most publications on (opto)electronic devices based on 2D materials rely on single monolayers embedded in classical 3D semiconductors, dielectrics and metals. However, heterostructures of different 2D materials can be employed to tailor the performance of the 2D components by reduced defect densities, carrier or exciton transfer processes and improved stability. This translates to additional and unique degrees of freedom for novel device design. The nearly infinite number of potential combinations of 2D layers allows for many fascinating applications. Unlike mechanical stacking, metal-organic vapour phase epitaxy (MOVPE) can potentially provide large-scale highly homogeneous 2D layer stacks with clean and sharp interfaces. Here, we demonstrate the direct successive MOVPE of MoS2/WS2 and WS2/MoS2 heterostructures on 2” sapphire (0001) substrates. Furthermore, the first deposition of large-scale MoS2/graphene and WS2/graphene heterostructures using only MOVPE is presented and the influence of growth time on nucleation of WS2 on graphene is analysed.
关键词： MOVPE,WS2,MoS2,heterostructures,2D materials,graphene,optoelectronic applications
更新于2025-09-23 15:19:57
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Nanoscale Interfaces of Janus Monolayers of Transition Metal Dichalcogenides for 2D Photovoltaic and Piezoelectric Applications
摘要： Using first-principles calculations, we demonstrate a combination of two emergent fields, type-II van der Waal heterostructures and Janus structures, for the purpose of optimizing the harvesting of solar and nanoelectromechanical energy. The most stable stacking order in these nanoscale heterobilayers comprising of Janus monolayers of transition metal dichalcogenides has been ascertained based on the interlayer binding energies. The binding energies in WSeTe/WSTe and MoSeTe/WSTe heterobilayers are found to be -27.93 and -25.67 meV/?2 at an equilibrium interlayer layer distance of 3.25 ? and 3.32 ? respectively, indicating the exothermicity in the process of heterobilayer formation and hence, its experimental feasibility. The mechanical and dynamical stabilities have also been confirmed for these heterobilayers using the Born Huang stability criteria and phonon dispersion calculations. Our results unveil the mechanism underlying the electronic, piezoelectric, photocatalytic properties and carrier mobility in these Janus heterobilayers. Power conversion efficiency in the 2D ultrathin excitonic solar cells constituted by some of the heterobilayers studied in this work, has been found to lie in the range of 15-20%. Moreover, a very high carrier mobility (>200 cm2/V.s) together with a large visible light absorption coefficient (α ~ 105 cm-1) has been observed in these hetero-bilayers. The piezoelectric coefficients in these ultrathin heterobilayers (d33 = 13.91 pm/V) is found to reach close to the values obtained in multilayer/bulk structures built from Janus monolayers of Mo-based dichalcogenides. Our findings highlight the promising applications of these heterobilayers in ultrathin excitonic solar cells, nanoelectronics and nanopiezotronics.
关键词： van der Waals heterostructures,transition metal dichalcogenides,photovoltaic applications,Janus monolayers,piezoelectricity,carrier mobility
更新于2025-09-23 15:19:57
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Scalable Synthesis of InAs Quantum Dots Mediated through Indium Redox Chemistry
摘要： Next-generation optoelectronic applications centered in the near-infrared (NIR) and short-wave infrared (SWIR) wavelength regimes require high-quality materials. Among these materials, colloidal InAs quantum dots (QDs) stand out as an infrared-active candidate material for biological imaging, lighting, and sensing applications. Despite significant development of their optical properties, the synthesis of InAs QDs still routinely relies on hazardous, commercially unavailable precursors. Herein, we describe a straightforward single hot injection procedure revolving around In(I)Cl as the key precursor. Acting as a simultaneous reducing agent and In source, In(I)Cl smoothly reacts with a tris(amino)arsenic precursor to yield colloidal InAs quantitatively and at gram scale. Tuning the reaction temperature produces InAs cores with a first excitonic absorption feature in the range of 700?1400 nm. A dynamic disproportionation equilibrium between In(I), In metal, and In(III) opens up additional flexibility in precursor selection. CdSe shell growth on the produced cores enhances their optical properties, furnishing particles with center emission wavelengths between 1000 and 1500 nm and narrow photoluminescence full-width at half-maximum (FWHM) of about 120 meV throughout. The simplicity, scalability, and tunability of the disclosed precursor platform are anticipated to inspire further research on In-based colloidal QDs.
关键词： colloidal synthesis,InAs quantum dots,short-wave infrared,optoelectronic applications,near-infrared
更新于2025-09-23 15:19:57
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Plasmonic Nanoparticles in Dielectrics Synthesized by Ion Beams: Optical Properties and Photonic Applications
摘要： The zero-dimensional metallic nanoparticles (NPs) have attracted tremendous attention in various areas owing to the collective oscillation of electron gas that couples with electromagnetic field, known as localized surface plasmon resonance (LSPR). In practical applications, the tailoring of LSPR effect is of significant importance for promising photonic devices with designed nanocomposite systems and enhanced optical properties. Ion beam technology has been demonstrated to be an efficient method to fabricate NPs embedded in dielectrics for LSPR tailoring and material modification. By manipulating the parameters of ion beams, the shape, size, and structure of NPs can be well controlled, which enables the dielectrics to possess novel linear and nonlinear optical properties. In this review, the latest research progress on the ion beam synthesis of various NPs is systematically summarized. The tailoring of linear and nonlinear optical properties of dielectrics by NPs is discussed in detail. Selected applications are presented to indicate the development of the plasmonic NPs in dielectric systems for photonic applications.
关键词： localized surface plasmon resonance,ion beam modification,nonlinear optical responses,photonic applications,plasmonic nanoparticles
更新于2025-09-23 15:19:57
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Narrow plasmonic surface lattice resonances with preference to asymmetric dielectric environment
摘要： Plasmonic surface lattice resonances (SLRs) supported by metal nanoparticle arrays exhibit narrow linewidths and enhanced localized ?elds and thus are attractive in diverse applications including nanolasers, biochemical sensors and nonlinear optics. However, it has been shown that these SLRs have much worse performance in a less symmetric environment, hindering their practical applications. Here, we propose a novel type of narrow SLRs that is supported by metal-insulator-metal nanopillar arrays and that has better performance in a less symmetric dielectric environment. When the dielectric environment is as asymmetric as the air/polymer environment with a refractive index contrast of 1.0/1.52, the proposed SLRs have high quality factors of 62 under normal incidence and of 147 under oblique incidence in the visible regime. We attribute these new SLRs to Fano resonance between an in-plane dipole and an out-of-plane quadrupole (or dipole) that are respectively supported by the two metal ridges under normal (or oblique) incidence. We also show that the resonance wavelength can be tuned by varying the geometric sizes or by changing the angle of incidence. By doing this, we clarify the conditions for the formation of the proposed SLRs and illustrate their attractive merits in sensing applications. We expect that this new SLR can open up applications in asymmetric dielectric environments.
关键词： sensing applications,asymmetric dielectric environment,Plasmonic surface lattice resonances,metal-insulator-metal nanopillar arrays,Fano resonance
更新于2025-09-23 15:19:57
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Special Issue on Optical Communications and Networking: Prospects in Industrial Applications
摘要： In the past two decades, Internet traffic has increased by over 10,000 times by taking advantage of both efficient information processing technology in the electronic domain and efficient transmission technology in the optical domain, which are the foundation of today’s Internet infrastructure [1,2]. The advancement of electronics processing circuits has followed Moore’s law, and perhaps will continue this exponential growth for years to come. This may make the electrical systems significantly outpace the advancement of optical systems in information and communications technologies. To support the ever-growing Internet traffic, optical communication systems face a great challenge in transporting information processed by electronic systems for sustained exponential growth. The industry has explored multiple degrees of freedom of the photon (time, wavelength, amplitude, phase, polarization, and space) to significantly reduce the cost/bit for data transmission by increasing the capacity/fiber through multiplexing and reducing the size and power through integration.
关键词： optical communication systems,networking,optical communications,industrial applications,Internet traffic
更新于2025-09-23 15:19:57
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Enhancement of the optical gain in GaAs nanocylinders for nanophotonic applications
摘要： Semiconductor nanolasers based on microdisks, photonic crystal cavities, and metallo-dielectric nanocavities have been studied during the last few decades for on-chip light source applications. However, practical realization of low threshold, room temperature semiconductor nanolasers is still a challenge due to the large surface-to-volume ratio of the nanostructures, which results in low optical gain and hence higher lasing threshold. Furthermore, the gain in nanostructures is an important parameter for designing all-dielectric metamaterial-based active applications. Here, we investigate the impact of p-type doping, compressive strain, and surface recombination on the gain spectrum and the spatial distribution of carriers in GaAs nanocylinders. Our analysis reveals that the lasing threshold can be lowered by choosing the right doping concentration in the active III–V material combined with compressive strain. This combination of strain and p-type doping shows 100× improvement in gain and approximately five times increase in modulation bandwidth for high-speed operation.
关键词： surface recombination,optical gain,compressive strain,GaAs nanocylinders,nanophotonic applications,p-type doping
更新于2025-09-23 15:19:57
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Editorial: Special Issue a??Laser-Induced Periodic Surface Nano- and Microstructures for Tribological Applicationsa??
摘要： Laser material processing is an innovative technology that generates surface functionalities on the basis of optical, mechanical, or chemical properties. In the form of laser surface texturing (LST), it has attracted a remarkable amount of research to tailor surface properties towards various tribological applications. Of this single-step, laser-based technology, the main advantages are the contactless machining, featuring a high flexibility, efficiency, and speed, along with the excellent quality of the processed products. LST can be applied precisely, localized to sub-micrometric areas, but, via laser beam scanning, it is also feasible for structuring large surface areas the size of square-meters.
关键词： microstructure,wear,laser-induced periodic surface structures (LIPSS),lubricant,applications,friction,tribology,nanostructure
更新于2025-09-23 15:19:57
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Breathing dynamics in a gain-guided dissipative soliton- similariton fiber laser
摘要： In this paper, the energy recovery in microstrip passive circuits from the power losses into heat is studied. For this purpose, a thermoelectric generator (TEG) based on the Seebeck effect principle is used, which converts part of the power dissipated into heat to dc electrical power. A solution integrating the TEG with the microstrip circuit is proposed, and design guidelines in order to optimize the recovered power keeping a good isolation between the RF signal and the TEG system are provided. As will be shown, under moderate applied signal powers of just 1–5 W, the levels of recovered power in microstrip passive circuits can be notable. As a demonstrator circuit, an integration device formed by an embedded microstrip bandpass filter for WiMAX applications and a TEG is designed, fabricated, and characterized (thermal and electrically). Different scenarios are considered, depending on frequency and thermal loads. For an applied in-band CW input signal power of 2 W at 3.48 GHz, a recovered power of around 250 μW has been continuously supplied to the electrical load. Several aspects, such as efficiency and future improvements, are also discussed.
关键词： power applications,Average power handling capability (APHC),microwave devices,planar circuits,energy recovery,electro-thermal analysis,energy harvesting
更新于2025-09-23 15:19:57
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Broadband, wide-angle antireflection in GaAs through surface nano-structuring for solar cell applications
摘要： We demonstrate broadband and wide-angle antireflective surface nanostructuring in GaAs semiconductors using variable dose electron-beam lithography (EBL). Various designed structures are written with EBL on a positive EB-resist coated GaAs and developed followed by shallow inductively coupled plasma etching. An optimized nanostructured surface shows a reduced surface reflectivity down to less than 2.5% in the visible range of 450–700 nm and an average reflectance of less than 4% over a broad near-infrared wavelength range from 900–1400 nm. The results are obtained over a wide incidence angle of 33.3°. This study shows the potential for anti-reflective structures using a simpler reverse EBL process which can provide optical absorption or extraction efficiency enhancement in semiconductors relevant to improved performance in solar photovoltaics or light-emitting diodes.
关键词： GaAs,surface nano-structuring,broadband,solar cell applications,wide-angle,antireflection
更新于2025-09-23 15:19:57