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Enhance the efficiency of green-yellow LED by optimizing the growth condition of preparation layer
摘要： The effects of the preparation layer grown under different conditions, which is an InGaN/GaN SLs structure inserted between the n-GaN layer and the MQWs, on the performance of green-yellow LED have been investigated. In this paper, the quality of InGaN/GaN multiple quantum wells (MQWs) and the optoelectronic properties of LED have been focused on. According to the experimental results, when the growth temperature of GaN barriers in SLs was increased, the interface between InGaN layers and GaN layers became more abrupt, and the indium distribution in the quantum wells became more uniform. In consequence, the forward voltage was reduced, the external quantum efficiency (EQE) was improved. By decreasing the growth rate of the high temperature barriers, the indium uniformity became even better, forward voltage was reduced again and EQE was further improved.
关键词： Preparation layer,Si substrates,Localized site,Crystal quality,Green-yellow LEDs
更新于2025-09-23 15:21:01
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Electrode design on plastic substrates using laser patterned double-sided tape and gold leaf
摘要： The production of electrodes and sensors using plastic substrates has increased substantially for the last decades. Although devices are fabricated using plastic substrates suitable for the purpose of each device, it is difficult to find a process that can be used commonly for most types of plastics. In this paper, two kinds of electrode fabrication process that can be applied to most plastic films using kapton double sided tape and gold leaf are proposed. One is for the plastic film with adhesive and the other is for the film without adhesive. First, the kapton double-sided tape was patterned using a CO2 laser. After transfer double-sided tape to desired substrate, release paper was detached and gold leaf was attached on the exposed side of the tape. Then, the tape was appropriately removed according to the presence or absence of the adhesive. After that, the packaging was performed using an adhesive when the used film has adhesive, and otherwise, heat press was used for packaging. These processes have a variety of advantages such as inexpensive, fast-running and commonly applicable to many plastics. To prove its usability, impedance and minimum line width was measured.
关键词： electrode fabrication,CO2 laser,kapton double-sided tape,plastic substrates,minimum line width,impedance,gold leaf
更新于2025-09-23 15:21:01
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[Laser Institute of America ICALEO?? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22a??26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Transformation of Gaussian beams into M-beams for advanced microvia drilling
摘要： Typical laser systems produce Gaussian laser beams that may not be suitable for high precision materials processing. This study considers laser microvia drilling of multilayer polymeric substrates for high density interconnects of microelectronics devices. Closely spaced microvias reduce the interconnect distance between the processors to meet the ever increasing demand for transferring large volumes of data at high rates. CO2 lasers of 9.3 μm wavelength is commonly used for drilling microvias in current polymeric substrates because of their higher absorption coefficient at this wavelength than at 10.6 μm wavelength of conventional CO2 lasers. High absorption coefficient provides a volumetric heating mechanism of shallow depth to enable surface-controlled vaporization of the polymeric materials. Gaussian or top-hat laser beams generally leave carbonized polymeric residue at the bottom corner and on the side wall of the microvias, and this residue hinders the subsequent microsoldering of electronic devices to the interconnects. The formation of the residue can be reduced using M-beams for microvia drilling. A thermal model is developed to determine the intensity distribution of the M-beam. To achieve this M-beam from a Gaussian beam, a lens system is designed using the Fresnel diffraction model. Drilling experiments have been conducted using an M-beam and the shape and size of the microvia are found to match the theoretical predictions very well.
关键词： microvia drilling,high density interconnects,Gaussian beams,CO2 lasers,M-beams,polymeric substrates
更新于2025-09-23 15:21:01
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Frontiers of Textile Materials (Polymers, Nanomaterials, Enzymes, and Advanced Modification Techniques) || Textiles in Solar Cell Applications
摘要： In previous years, the energy requirement has enhanced dramatically in the world. There are many energy sources have been developed but solar energy is one of the most promising energy techniques. Moreover, the solar energy is a never ending process and has higher potential in the future world. The conventional solar cells array has been commercialized which uses glass fronted panels. However, these kinds of solar cells array are not suitable and require a light weight flexible solar cell generator/substrates. Textiles are the most suitable candidate for their potential applications in solar cells. Textiles based solar cells could be developed for flexible and wearable purposes. In this chapter, we have discussed the properties of textiles, general principle of solar cells and fabrication of textiles based solar cells. This chapter also complied and discussed the recent advancement in the development of solar cells using textiles.
关键词： solar cells,Textiles,photovoltaics,electrode substrates
更新于2025-09-23 15:21:01
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Optimizing the SERS Performance of 3D Substrates through Tunable 3D Plasmonic Coupling toward Label-free Liver Cancer Cell Classification
摘要： Three-dimensional (3D) plasmonic nanostructures are emerging as excellent surface-enhanced Raman spectroscopy (SERS) substrates for chemical and biomedical applications. However, the correlation of the 3D (including both of the in-plane and out-of-plane) plasmonic coupling with the SERS properties to deepen the understanding of 3D SERS substrates remains a challenge. Here, we perform correlated studies of 3D plasmonic coupling and SERS properties of the 3D hierarchical SERS substrates by tuning the multiscale structural elements. The effect of 0D (the size of building blocks), 1D (the thickness of the 3D substrates) and 2D (the composition of individual monolayers) structural elements on 3D plasmonic coupling are studied by measuring the UV-Vis-NIR spectroscopy and SERS performance. It shows that both of the extinction spectra and SERS enhancement are tuned at the 3D structural level. It is demonstrated that the plasmonic resonance wavelength (PRW) stemmed from the 3D plasmonic coupling is correlated with the SERS averaged surface enhancement factor (ASEF), and which is improved by over 10-fold at the optimum 3D nanostructure. The optimized substrate is used to quantitatively analyze two small biological molecules. Moreover, as a proof-of-concept study, the substrate is first applied to differentiate between living liver normal and cancer cells with a high prediction accuracy through the spectral features of the cell membranes and the metabolites secreted outside the cells. We expect that the tuning of plasmonic coupling at 3D level can open up new routes to design high performance SERS substrates for wide applications.
关键词： liver cells,3D substrates,3D plasmonic tuning,SERS,structural parameters
更新于2025-09-23 15:21:01
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Reference Module in Materials Science and Materials Engineering || Organometallic Vapor Phase Epitaxial Growth of Group III Nitrides ☆
摘要： The III-nitrides of aluminum nitride (AlN), gallium nitride (GaN), and indium nitride (InN) and their solid solutions form most commonly in the low-temperature wurtzite crystal structure shown in Fig. 1(a). Overall, this structure possesses a hexagonal unit cell with lattice constants c (o00014 axes) and a (o11204 axes). The atomic arrangement within this structure consists of two interpenetrating, closest packed metal and nitrogen lattices in which each atom of one type is bonded to four atoms of the other to form AB4 tetrahedra. The space group is P63mc.
关键词： GaN,OMVPE,Organometallic Vapor Phase Epitaxy,Group III Nitrides,Polarization,Dislocations,InN,Buffer Layers,AlN,Substrates
更新于2025-09-23 15:21:01
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Making thick photoresist SU-8 flat on small substrates
摘要： This work suggests a simple method to ?atten thick layers ((cid:24) 50(cid:0)200 (cid:22)m) of SU-8 photoresist on small substrates ((cid:24) 1 cm). The method sidesteps the edge beads problem and enables photolithography patterns up to the substrates’ edges. Moreover, the method can be used even for substrates with large aspect ratios when the spin coating is largely impossible.
关键词： edge beads,SU-8 uniformity,small substrates
更新于2025-09-23 15:21:01
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Interfacial structure of SrZr <sub/><i>x</i> </sub> Ti <sub/>1?</sub><sub/><i>x</i> </sub> O <sub/>3</sub> films on Ge
摘要： The interfacial structure of SrZrxTi1?xO3 films grown on semiconducting Ge substrates is investigated by synchrotron X-ray diffraction and first-principles density functional theory. By systematically tuning the Zr content x, the effects of bonding at the interface and epitaxial strain on the physical structure of the film can be distinguished. The interfacial perovskite layers are found to be polarized as a result of cation-anion ionic displacements perpendicular to the perovskite/semiconductor interface. We find a correlation between the observed buckling and valence band offsets at the SrZrxTi1?xO3/Ge interface. The trends in the theoretical valence band offsets as a function of Zr content for the polar structures are in agreement with reported X-ray photoelectron spectroscopy measurements. These results have important implications for the integration of functional oxide materials with established semiconductor based technologies.
关键词： synchrotron X-ray diffraction,density functional theory,valence band offsets,SrZrxTi1?xO3 films,Ge substrates,interfacial structure
更新于2025-09-23 15:21:01
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Facilitating Tip-Enhanced Raman Scattering on Dielectric Substrates via Electrical Cutting of Silver Nanowire Probes
摘要： TERS is a powerful tool for nanoscale optical characterization of surfaces. However, even after 20 years of development, the parameters for optimal TERS tips are still up for debate. As a result, routine measurements on bulk or dielectric substrates remain exceptionally challenging. Herein we help to alleviate this by using electrical cutting to strategically modify silver nanowire TERS probes. Following cutting, the tips present a large, spherical apex and are often nanostructured with numerous nanoparticles, which we argue improve light collection and optical coupling. This doubles TERS signals on a highly-enhancing, gap-mode substrate compared to our standard nanowire tips, whilst maintaining a high reproducibility and resolution. More interestingly, on a dielectric substrate (graphene on SiO2) the tips give ~7x higher signals than our standard tips. Further investigations point to the non-local nature of the enhancement using standard, smooth, TERS probes without gap-mode, making such nanostructuring highly beneficial in these cases.
关键词： electrical cutting,silver nanowire,TERS,Tip-Enhanced Raman Scattering,nanoscale optical characterization,dielectric substrates
更新于2025-09-23 15:21:01
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Tensilely Strained Ge Films on Si Substrates Created by Physical Vapor Deposition of Solid Sources
摘要： The development of Si-compatible active photonic devices is a high priority in computer and modern electronics industry. Ge is compatible with Si and is a promising light emission material. Nearly all Ge-on-Si materials reported so far were grown using toxic precursor gases. Here we demonstrate the creation of Ge films on Si substrates through physical vapor deposition of toxin-free solid Ge sources. Structural characterization indicates that a high tensile strain is introduced in the Ge film during the deposition process. We attribute the presence of such a tensile strain to the difference in thermal expansion coefficient between Si and Ge. A Ge peak, centered at ~2100 nm, is evident in the photoluminescence spectra of these materials, which might result from direct band gap photoluminescence alone, or from superposition of direct band gap and indirect band gap photoluminescence. These Ge-on-Si materials are therefore promising in light emission applications.
关键词： tensile strain,Si substrates,physical vapor deposition,Ge films,photoluminescence
更新于2025-09-23 15:21:01