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High-performance amorphous BeZnO-alloy-based solar-blind ultraviolet photodetectors on rigid and flexible substrates
摘要： In this study, the bandgap of ternary alloy BeZnO was modulated to make the material applicable to solar-blind ultraviolet (UV) radiation detection. This was done by preparing amorphous films with high Be doping contents on rigid c-sapphire and flexible polyethylene terephthalate (PET) and polyethylene naphthalene (PEN) substrates. After depositing a pair of parallel Al electrodes, amorphous BeZnO-alloy-based solar-blind UV photodetectors (PDs) with peak responsivity occurring at around 230 nm were constructed and their cut-off wavelengths are less than 284 nm. The PDs constructed on three substrates exhibit extremely low dark currents of 58.7 pA, 2.9 pA, and 1.8 pA, respectively. Time-dependent photoresponse cycling confirmed devices reproducible, and sensitive to solar-blind UV radiation. More importantly, the devices exhibited fast response speeds with rise times of approximately 40 ms and particularly fast recovery speeds with decay times of approximately 10 ms. Our research provides a method of constructing high-performance PDs on various substrates. And constructing amorphous solar-blind UV PDs on flexible substrate in this work is expected to be guiding significance to the design of PDs with deformability.
关键词： Amorphous BeZnO alloy,Fast recovery speed,Solar blind photodetectors,Flexible substrate,High Be content
更新于2025-09-23 15:21:01
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Roles of chemistry modification for laser textured metal alloys to achieve extreme surface wetting behaviors
摘要： Wetting behaviors of structured metal surfaces have received considerable attention due to the wide range of applications for commercial, industrial, and military uses as well as fundamental research interests. Due to its adaptability, precision, and ease of automation, laser-based texturing techniques are desirable platforms to create micro- and nano-structures, including laser-induced periodic surface structures, or hierarchical structures on a metal substrate. However, micro- and nanostructures alone often do not achieve the desired wettability. A subsequent surface chemistry modification method must be performed to attain target extreme wettability for laser textured metal substrates. This review aims to provide a systematic understanding of the interdependence of surface chemistry modification and physical surface structures formed during the laser-based surface engineering methods. The role of surface chemistry on top of the surface structures is presented to decide the final wetting scenario. Specifically, by controlling the surface chemistry of a laser textured surface, wetting can be modulated from extreme hydrophobicity to hydrophilicity, allowing freedom to achieve complex multi-wettability situations. In each section, we highlight the most fruitful approaches and underlying mechanisms to achieve a fitting combination of surface structures and surface chemistry. Durability and stability of the treatd surface is also discussed in corrosive and abrasive environments. Finally, challenges in current studies and prospects in future research directions of this rapidly developing field are also discussed. This review will provide a comprehensive guideline for the design of laser texturing methods and the fabrication of extreme wetting surfaces for metal alloys.
关键词： superhydrophilicity,superhydrophobicity,metal alloy,Laser surface texturing,chemistry modification,silane treatment
更新于2025-09-23 15:21:01
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Ternary PtNiCu self-assembled nanocubes for plasmon-enhanced electrocatalytic hydrogen evolution and methanol oxidation reaction in visible light
摘要： The strong interaction among metal components results in the change of the electronic structure (e.g. d-band energy level) of noble metal-based alloy structures which enables the increase of catalytic activity. In this paper, self-assembled ternary PtNiCu and binary PtCu alloy nanocubes are synthesized by a one-pot high-temperature chemical reduction method. The growth mechanism of the alloy is investigated. The alloy is applied to visible light-assisted electrocatalytic hydrogen production and methanol oxidation. The ternary PtNiCu alloy exhibits superior catalytic performance (a minimum over potential of 15 mV at a current density of 10 mA cm-2, a Tafel slope of 24.1 mV/dec, and more excellent mass specific activity under visible light irradiation about 3.3 A mgPt -1), because of its regular morphology, more surface active sites, and more intense interaction between metal elements. Especially the localized surface plasmon resonance effect of Cu largely increases the electron density (photoelectric effect) on Pt under illumination, thereby further improves the photo-assisted hydrogen production and methanol catalytic oxidation performance. The results will promote efficient and accurate electrocatalysis process, paving new way for a brighter further in rational design of ternary plasmonic electrocatalysts and photoelectrocatalysis field.
关键词： Methanol oxidation reaction,Photoelectrocatalysis,Hydrogen evolution reaction,Ternary PtNiCu alloy
更新于2025-09-23 15:21:01
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Effects of the Nozzle Tip Clogging and the Scanning Direction on the Deposition Process During Laser Metal Deposition of Alloy 718 Using a Four-Stream Discrete Nozzle
摘要： Depending on the configuration of the LMD system, the nozzle tilting is necessary to be able to manufacture parts with complex geometry. In these cases, the use of discrete coaxial nozzles is recommended. With this type of nozzle, the powder can clog the internal tips of the nozzle streams due to an inappropriate shape, size distribution, humidity or temperature conditions of the powder particles during the deposition process. This undesired effect can be an opportunity depending on the combination of the activated powder tips for coating complex surfaces when the geometry of the substrate acts as a barrier for the powder stream. This work presents for first time the effect of the scanning direction and the stream clogging on the deposition process in terms of powder efficiency, Material Deposition Rate (MDR) and clad geometry and dimensions, when Alloy 718 is deposited by LMD using a four-stream discrete coaxial nozzle.
关键词： Alloy 718,coatings,Laser metal deposition,geometrical characteristics,stream clogging,discrete nozzle
更新于2025-09-23 15:21:01
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Suggestions on Efficiency Droop of GaN-based LEDs
摘要： InGaN/GaN-based light-emitting diodes (LEDs) are widely used in modern society and industry among different areas. However, InGaN/GaN LEDs suffer from an efficiency droop issue: The internal efficiency decreases during high current injection. The efficiency droop significantly affects the development of GaN-based LEDs devices in efficiency and light-output areas. Therefore, the improvement of the droop phenomenon has become a significant topic. This paper introduces several possible mechanisms of droop phenomenon based on different hypotheses including Auger Recombination, Carrier Delocalization and Electron Leakage. Furthermore, some proposals to mitigate efficiency droop, including semipolar LEDs, electron blocking layer(EBL), quaternary alloy and chip design will be discussed and analyzed. Also, it will provide some suggestions for the further optimization of droop phenomenon in each proposal.
关键词： electron blocking layer,semipolar LEDs,GaN-based LEDs,Auger Recombination,chip design,quaternary alloy,Carrier Delocalization,Electron Leakage,efficiency droop
更新于2025-09-23 15:21:01
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Improvement of the Laser-Welded Lap Joint of Dissimilar Mg Alloy and Cu by Incorporation of a Zn Interlayer
摘要： During pulsed laser welding of AZ 31B magnesium (Mg) alloy and T2 pure copper (Cu), Cu2Mg and Mg2Cu are generated, but the bonding ability of the two compounds is usually weak, resulting in low strength. In order to improve the joint of two dissimilar metals, a zinc interlayer was inserted between the Mg alloy and Cu, and the effects of the thickness of the Zn interlayer on the microstructure and properties of the joint were studied. The fused zone consisted of Cu2Mg and MgZn, and, according to first-principles calculation, in the same energy range, the area enclosed by the density of the state curve of MgZn was larger than that of Cu2Mg. Hence, the bonding ability of MgZn was better than that of Cu2Mg, and MgZn improved the strength of the welded joint. The most advantageous thickness of the Zn interlayer was 0.1 mm, and the shear strength was 48.15 MPa that was 161% higher than that of the directly welded Mg/Cu joint.
关键词： interlayer,first-principles calculation,magnesium alloy,laser welding,dissimilar metals
更新于2025-09-23 15:21:01
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Pore Formation during Laser Welding in Different Spatial Positions
摘要： The process of formation of pores, cavities and similar defects in welded joints of stainless steels and aluminum alloys, affecting their quality, directly depends on spatial weld position in laser welding. Reducing the angle of inclination from 90° to 0° during downhill and uphill welding of AISI 321 stainless steel in the pulse mode of laser generation leads to an increase in both the number of pores and their size. At the same time, defects in the form of pores are not observed in the continuous mode of laser generation. In laser welding of butt joints of AISI 321 steel, the flat and vertical weld positions are the most promising, as they provide the highest level of quality. In order to provide a stable formation of a high-quality butt joint of aluminum AMg6M alloy and to prevent the failure of laser equipment, the welding process should be carried out in a vertical uphill weld position.
关键词： different spatial position,aluminium alloy,stainless steel,quality,defects,porosity,laser welding
更新于2025-09-23 15:21:01
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Excitonic complexes in InAs/InP nanowire quantum dots
摘要： InAs quantum dots embedded in InP nanowires form an important platform for basic research studies, as well as for quantum dot applications. Notably, understanding of nanowire quantum dot spectral properties is essential in both cases. Therefore, in this work we use atomistic theory to study spectra of the single exciton (X ), the biexciton (X X ), the triexciton (X X X ), and the positively and negatively charged trions (X + and X ?) con?ned in these nanostructures. We focus on the role of vertical and lateral con?nement, therefore, we systematically study a large family of quantum dots with different heights and diameters, and ?nd the important role of correlations due to presence of higher states. We ?nd that the order of excitonic binding energies is a characteristic feature of InAs/InP nanowire quantum dots being (ordered from negative to positive values): X ?, X X , and X +, with strongly bound X ?, rather weakly bound X X , and typically unbound X +. Next, we determine the key role of alloy randomness due to intermixing, which turns out to especially important for larger quantum dot heights and phosphorous contents over 40%. In selected cases, the alloying can lead to an unbound biexciton, and can even reverse ordering of excitonic lines.
关键词： InAs/InP nanowire quantum dots,atomistic theory,binding energies,alloy randomness,excitonic complexes
更新于2025-09-23 15:21:01
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Bandgap tunable Zn3-3Mg3N2 alloy for earth-abundant solar absorber
摘要： Zn3-3xMg3xN2 alloy layers with x ≤ 0.3 can be epitaxially grown at a temperature as low as 140 oC. The bandgap (Eg) of Zn3-3xMg3xN2 widens from 1.2 to 2.1 eV with increasing x. The Eg value of 1.4 eV is obtained at x = 0.18, and the x = 0.18 film has a large absorption coefficient (104-105 cm-1) in the visible region. The Zn3-3xMg3xN2 with Eg = 1.4 eV shows n-type conductivity with a reasonably high electron mobility of 47 cm2 V-1 s-1. Therefore, Zn3-3xMg3xN2 is a candidate for an earth-abundant solar absorber that can be fabricated at low temperatures.
关键词： Nitride alloy,Bandgap tunability,Photovoltaic semiconductors,Sputtering
更新于2025-09-23 15:21:01
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Influence of ion species of AuSi liquid metal alloy source-focused ion beam on SiO2/Si nanopatterning
摘要： This work investigates the influence of the ion source (Au+ and Si+2 ions) of liquid metal alloy source-focused ion beam on the nanopattering. Two sets of SiO2/Si nanopatterns with a width of 450 nm on Silicon on insulator (SOI) substrate are fabricated by 30 keV Au+ and Si+2 ions, respectively. To study this effect, the sputtering yield is calculated using the volume loss method from atomic force microscopy (AFM) profiles obtained for each set. The results of the sputtering yield were compared with theoretical results calculated from Yamamura model for normal incidence for validation. The comparison showed a good agreement between the two results with a relative difference of about 5.3 % obtained using Si+2 ions.
关键词： Liquid metal alloy source-focused ion beam,Milling,Sputtering yield,Nanopattering
更新于2025-09-23 15:21:01