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Prediction of MCO [M = S, (Cl <sub/>2</sub> B) <sub/>3</sub> B] Systems with Giant Optical Birefringence and Nonlinearity in the Deep-Ultraviolet Region
摘要： Deep-ultraviolet (DUV) materials with giant optical birefringence and nonlinearity are scarce, and their discovery is very challenging. In this Communication, we predict that the MCO [M = S, (Cl2B)3B] compounds containing the polar C?O motif, which have been synthesized in the experiments, could be the ?rst material systems to achieve this rare capability. First-principles calculations demonstrate that (Cl2B)3BCO and SCO exhibit the largest second-harmonic-generation e?ect (～4.4 pm/V) and the largest birefringence (～0.6) in all known DUV nonlinear-optical (NLO) crystals. In addition, SCO might be a DUV NLO material for the practical 193.7 nm laser output. Our discovery could enrich the structural chemistry of NLO crystals and advance the development of functional DUV optical materials.
关键词： Deep-ultraviolet,nonlinearity,polar C?O motif,DUV nonlinear-optical crystals,first-principles calculations,MCO compounds,second-harmonic-generation,optical birefringence
更新于2025-09-23 15:19:57
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Facile organic surfactant removal of various dimensionality nanomaterials using low-temperature photochemical treatment
摘要： Deep ultraviolet (DUV)-treatment is an efficient method for the removal of high-energy-barrier polymeric or aliphatic organic ligands from nanomaterials. Regardless of morphology and material, the treatment can be used for nanoparticles, nanowires, and even nanosheets. The high-energy photon irradiation from low-pressure mercury lamps or radio frequency (RF) discharge excimer lamps could enhance the electrical conductivity of various nanomaterial matrixes, such as Ag nanoparticles, Bi2Se3 nanosheets, and Ag nanowires, with the aliphatic alkyl chained ligand (oleylamine; OAm) and polymeric ligand (polyvinyl pyrrolidone; PVP) as surfactants. In particular, Ag nanoparticles (AgNPs) that are DUV-treated with polyvinyl pyrrolidone (PVP) for 90 min (50–60 °C) exhibited a sheet resistance of 0.54 Ω □?1, while thermal-treated AgNP with PVP had a sheet resistance of 7.5 kΩ □?1 at 60 °C. The simple photochemical treatment on various dimensionality nanomaterials will be an efficient sintering method for flexible devices and wearable devices with solution-processed nanomaterials.
关键词： nanomaterials,organic ligand removal,photochemical treatment,electrical conductivity,deep ultraviolet
更新于2025-09-19 17:15:36
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Enhanced photoresponse and surface charge transfer mechanism of graphene-tungsten disulfide heterojunction
摘要： Two dimensional (2D) materials based heterostructures have gained profound interest in optoelectronics and electronic technology due to additional functionalities over the individual structures. This study demonstrates the fabrication and characterization of van der Waal heterostructure by selective coverage of graphene (Gr) with tungsten disulfide (WS2). The electrical transport measurements divulge the tweaking of charge carriers in graphene after WS2 coverage. Such architecture provides route towards the formation of heterojunction within graphene FET based on surface charge transfer between Gr/WS2 heterointerface. Furthermore, the exposure of device towards deep ultraviolet light (DUV) enhances the charge transfer mechanism and as a result more pronounced junction is observed. The photoelectrical characterization of heterostructure is also investigated by calculating detectivity (D*), external quantum efficiency (EQE) photoresponsivity (Rλ). Our results suggest that 2D heterostructures in combination with DUV irradiations are more efficient and suitable choice to selectively tune the properties of 2D material-based optoelectronic devices.
关键词： p-n junction,Tungsten disulfide,Graphene,Photoresponse,Deep ultraviolet light (DUV),Heterostructure
更新于2025-09-19 17:13:59
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Enhanced Emission of Deep Ultraviolet Light-Emitting Diodes Through Using Work Function Tunable Cu Nanowires as Top Transparent Electrode
摘要： Deep ultraviolet light-emitting diodes (DUV LEDs) (< 280 nm) have been important light sources for broad applications in, e.g., sterilization, purification, high-density storage and etc. However, the lack of excellent transparent electrodes in DUV region remains a challenging issue. Here, we demonstrate an architectural engineering scheme to flexibly tune the work function of Cu@shell nanowires (NWs) as top transparent electrodes in DUV LEDs. By fast encapsulation of shell metals on Cu NWs and shift of electron binding energy, the electronic work function could be widely tailored down to 4.37 eV and up to 5.73 eV. It is revealed that the high work function of Cu@Ni and Cu@Pt NWs could overcome the interfacial barrier to p-AlGaN and achieve direct ohmic contact with high transparency (91%) in 200 ~ 400 nm. Completely transparent DUV LED chips are fabricated and successfully lighted with sharp top emission (wall-plug efficiency reaches 3 %) under a turn-on voltage of 6.4 V. This architectural strategy is of importance in providing highly transparent ohmic electrodes for optoelectronic devices in broad wavelength regions.
关键词： copper nanowires,transparent electrodes,light-emitting diodes,Deep ultraviolet,work function
更新于2025-09-19 17:13:59
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Suppression of efficiency droop in AlGaN based deep UV LEDs using double side graded electron blocking layer.
摘要： We have envisaged and designed a novel III-V Nitride based deep ultraviolet light emitting diodes (DUV LEDs) with reasonably high efficiency at higher current density using a double-side grading in electron blocking layer (EBL). Double-side step- and linear-grading in EBL yield better performance attributable to improved hole injection, stifled electron overflow and diminished electrostatic field in the active region. The performance curves indicate that double sided linear grading in EBL has 5.63 times enhancement in power compared to the conventional LED and the efficiency droop is as low as 15% at the current density of 200 A/cm2 for the emission wavelength of ~273 nm.
关键词： Double side compositional grading,Electron Blocking Layer (EBL),Internal Quantum Efficiency (IQE),Deep Ultraviolet (DUV) LEDs
更新于2025-09-19 17:13:59
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MXene Enhanced Deep Ultraviolet Photovoltaic Performances of Crossed Zn <sub/>2</sub> GeO <sub/>4</sub> Nanowires
摘要： Zn2GeO4 crystal is an ideal semiconductor for deep ultraviolet detection due to its wide-bandgap of ~4.69 eV. To further improve its DUV performance, two-dimensional MXenes with high electrical conductivity, potentially tunable electronic structure and nonlinear optical properties were applied on crossed Zn2GeO4 nanowires network materials. The results presented here show that the DUV detectors based on Zn2GeO4/MXene hybrid nanostructure exhibited excellent optoelectronic performances with a largest responsivity of 20.43 mA/W and external quantum efficiency of 9.9% under 254 nm wavelength light illumination. The excellent optical performance is from the synergistic effect of MXene and Zn2GeO4 nanowires. The metallic property of MXene provide a fast electron-transport for Zn2GeO4/MXene, which leads to larger photocurrent and fast photo response. The construction of unique semiconductive-conductive networks and large interfaces of Zn2GeO4 NWs, MXene layers, and the interfaces between them also promotes photo-induced electron-hole separation in the sample. Considering the large amount of members in MXene, this study demonstrates a new strategy applicable in maximizing their applications in deep ultraviolet photodetectors.
关键词： photodetectors,nanowires,deep ultraviolet,Zn2GeO4,MXene
更新于2025-09-19 17:13:59
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Solar-blind deep-ultraviolet photodetectors based on solution-synthesized quasi-2D Te nanosheets
摘要： Solar-blind deep ultraviolet (DUV) photodetectors with high responsivity (R) and fast response speed are crucial for practical applications in astrophysical analysis, environmental pollution monitoring, and communication. Recently, 2D tellurium has emerged as a potential optoelectronic material because of its excellent photoelectric properties. In this study, solar-blind DUV photodetectors are demonstrated based on solution-synthesized and air-stable quasi-2D Te nanosheets (Te NSs). An R of 6.5×104 A/W at 261 nm and an external quantum efficiency (EQE) of higher than 2.26×106% were obtained, which are highest among most other 2D material-based solar-blind DUV photodetectors. Moreover, the photoelectric performance of the quasi-2D Te-based photodetector exhibited good stability even after ambient exposure for 90 days without any encapsulation. These results indicate that quasi-2D Te NSs provide a viable approach for developing solar-blind DUV photodetectors with ultrahigh R and EQE.
关键词： FET,photodetector,solar-blind deep ultraviolet,quasi-2D Te nanosheets
更新于2025-09-19 17:13:59
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Band engineering of III-nitride-based deep-ultraviolet light-emitting diodes: A review
摘要： III-nitride deep ultraviolet (DUV) light-emitting diodes (LEDs) are identified as the promising candidate for energy-efficient, environment-friendly and robust UV lighting source in the application of water/air purification, sterilization, and bio-sensing. However, the state-of-art DUV LED performance is far from satisfaction for commercialization owing to its low internal quantum efficiency, large current leakage and efficiency droop at high current injection, etc. Extensive efforts have been devoted to properly designing the band structures of such luminescent devices to enhance their output power. In this review, we summarize the recent progress on various energy band designs and engineering of DUV LEDs, with particular of interest is paid on the various approaches in band engineering of the electron-blocking layer, quantum well, quantum barrier and the implementation of many novel structures such as tunnel junctions, ultrathin quantum heterostructures to enhance their efficiency. Those inspirational approaches pave the way towards the next generation of greener and efficient UV sources for practical applications.
关键词： Quantum well,Quantum barrier,Deep ultraviolet light-emitting diode,Ultrathin quantum heterostructures,Band engineering,Electron-blocking layer,Tunnel junctions,III-nitride
更新于2025-09-19 17:13:59
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TE/TM mode full-spatial decomposition of AlGaN-based deep ultraviolet light-emitting diodes
摘要： The full-spatial decomposition of transverse electric (TE) / transverse magnetic (TM) mode in AlGaN-based deep ultraviolet light-emitting diodes (DUV-LEDs) has been experimentally investigated, by introducing self-built light intensity test system mainly composed of angle resolution bracket, Glan-Taylor prism and spectrometer. By means of roughening the sapphire sidewall, the extraction efficiency of DUV-LED is improved, for both TE and TM mode light with no polarization selectivity. The introduction of self-built light intensity metrology system has been reflected via scribing the sapphire sidewalls using various laser conditions, which show a reliability in the enhancement validation of the light extraction efficiency. More importantly, the self-built light intensity test system enables effective feedback on epitaxial structures and chip structure design and provides a new perspective to design high efficiency AlGaN-based DUV-LEDs.
关键词： AlGaN,TE/TM mode light,sapphire sidewall roughening,deep ultraviolet light emitting diodes
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Sub-Decibel Off-Chip Fiber Couplers Based on L-Shaped Waveguides and Subwavelength Grating Metamaterials
摘要： Uniform grating couplers based on versatile L-shaped waveguides are experimentally demonstrated, with coupling loss of -2.7 dB and back-reflections of -20 dB. Apodized couplers with subwavelength-grating metamaterials predict improved fiber-chip coupling down to -0.46 dB within device layouts compatible with lithographic technologies available in nanophotonic foundries.
关键词： silicon-on-insulator,sub-wavelength grating metamaterials,deep-ultraviolet technology,silicon nanophotonics,grating couplers,mass-scale production
更新于2025-09-16 10:30:52