Industrial Lead Research Articles

Mini Light‐Emitting Diode Technology with High Quantum Efficient NIR‐II Partially Inverse Spinel MgGa2O4:Cr3+,Ni2+ Nanophosphors

AbstractThe increasing demand for second near‐infrared (NIR‐II) region materials, which retain the advantage of minimal scattering and immense applications in the medical and NIR spectroscopy field, has led to considerable research in this region. A mini light‐emitting diode (mini‐LED) is essential for backlighting liquid crystal displays, indicating the need for the small size of phosphors. However, current market phosphors must be more significant to be a viable option for mini‐LEDs. This scenario necessitates the synthesis of small‐sized phosphors to be used in mini‐LEDs. In this work, a mesoporous silica nanoparticle (MSN) and incorporated the Mg1−yGa2−xO4:xCr3+,yNi2+ system is fabricated. The structural investigation confirmed the single phase of MgGa2O4 with a pore size of 2.73 nm for the MSN. The results showed a steady NIR‐II signal at 1270 nm and an enhanced energy transfer with a high quantum yield of 79.2% for a nanophosphor. The mini‐LED package revealed a 1000–1600 nm signal, qualifying the nanophosphor for realistic applications. This work can make provisions for various NIR‐II nanophosphors in the LED industry.

Effects of cerium oxide and cerium sulfate on the optical behavior of synthesized garnet glass ceramics

In this study, the YAG silicate glasses containing the cerium sulfate and cerium oxide salts (17YO3-33Al2O3-40SiO2-2AlF3-3NaF-2CeO2-3B2O3), separately were produced by melting method and glass ceramics were produced by heat treatment of base glasses. According to Photo Luminescence spectrums of both glasses there were emissions in the range of 466 and 435 nm wavelengths related to cerium ions. It was shown that by heating treatment, garnet crystal (in sulfated sample) formed less than the sample with cerium oxide. The emission spectra of both glass-ceramics, when excited at 240 nm, fall within the wavelength range of 460 nm. Also, the 534 and 660 nm emissions wavelengths were obtained by 340 nm wavelength excitation. Heat treatments were done by oxide atmosphere in tubular furnace (single step), SPS sintered powder and in hydrogen atmosphere (by two steps heating). According to XRD results the 24 hrs. heat treating time and the 1060 °C temperature affect the entry of cerium into the garnet structure. Finally, by comparing the spectroscopic results the optical response of the garnet glass-ceramic synthesized in the hydrogen atmosphere was obtained at 400 nm wavelength that indicated this garnet can be applied in the LED industry.

A sustainable process for selective recovery of metals from gallium-bearing waste generated from LED industry

With the rapid development of the LED industry, gallium (Ga)-bearing waste generated is regarded as one of the most hazardous as it typically contains heavy metals and combustible organics. Traditional technologies are characterized by long processing routes, complex metal separation processes and significant secondary pollution emission. In this study, we proposed an innovative and green strategy to selectively recovery Ga from Ga-bearing waste by using a quantitative phase-controlling transition process. In the phase-controlling transition process, the gallium nitride (GaN) and indium (In) are converted to alkali-soluble gallium (III) oxide (Ga2O3) and alkali-insoluble indium oxides (In2O3) by oxidation calcination, while nitrogen is converted into diatomic nitrogen gas instead of ammonia/ammonium (NH3/NH4+). By selective leaching with NaOH solution, nearly 92.65% of Ga can be recycled with a leaching selectivity of 99.3%, while little emissions of NH3/NH4+. Ga2O3 with a purity of 99.97% was obtained from the leachate which is also economy promising by economic assessment. Therefore, the proposed methodology compared to the conventional acid and alkali leaching methods is potentially greener and more efficient process for extracting valuable metals from nitrogen-bearing solid waste.

A Sustainable Process for Selective Recovery of Metals from Gallium-Bearing Waste Generated from Led Industry

A Sustainable Process for Selective Recovery of Metals from Gallium-Bearing Waste Generated from Led Industry

Trends and Technologies in LED Industries

Trends and Technologies in LED Industries

Russian and Chinese strategy of participation in global value chains: case study (the production of led lamps)

In the scientific literature the participation of a country in global value chains (GVCs) is considered from different points of view corresponding to several theories. Proponents of the neoclassical approach argue that participation in the chain brings benefits in itself. The concept of "economic advancement" implies the involvement of some development institutions. To date, a number of empirical studies have accumulated that criticize both approaches. In the paper, the (GVCs) of LED lamps, which are presented on the Russian market, are considered. The obstacles to increasing the added value that Russia faces at each stage are identified, and the main hindrance for domestic companies in this industry is revealed, that is, the impossibility of price competition with Chinese manufacturers. The paper provides an overview of the measures taken by China to develop the LED industry. From the above example, it follows that the goal of China's strategy is not just to increase the added value at each individual stage of production, but to assert Chinese dominance in the entire chain. This problem is solved by establishing control over its most important link and the subsequent transfer of all other stages of production to the territory of China.

Piezoelectric relaxation of two-dimentional electron gas in InGaN/GaN heterostructures with quantum wells

The article is devoted to the study of the mechanism of piezoelectric scattering of charge carriers in an InGaN/AlGaN/ GaN heterostructures with one filled quantum-confinement subband. The aim of the article is to create a mathematical model that can be used to estimate the kinetic parameters of a two-dimensional electron gas (2DEG) in the structure under study. The results of the calculation of the matrix scattering potentials demonstrated the reliability and consistency on the used model of industrial LED heterostructures with InGaN/GaN quantum wells. It is shown that mechanical stresses in the InGaN/GaN layers lead to an uneven distribution of the total electric field along the active layer. It has been established that the lifetime limiting the mobility of a two-dimensional electron gas in piezoelectric scattering is of the order of 10–9 s.

Пьезоэлектрическая релаксация двумерного электронного газа в гетероструктурах с квантовыми ямами InGaN/GaN

The article is devoted to the study of the mechanism of piezoelectric scattering of charge carriers in an InGaN/AlGaN/ GaN heterostructures with one filled quantum-confinement subband. The aim of the article is to create a mathematical model that can be used to estimate the kinetic parameters of a two-dimensional electron gas (2DEG) in the structure under study. The results of the calculation of the matrix scattering potentials demonstrated the reliability and consistency on the used model of industrial LED heterostructures with InGaN/GaN quantum wells. It is shown that mechanical stresses in the InGaN/GaN layers lead to an uneven distribution of the total electric field along the active layer. It has been established that the lifetime limiting the mobility of a two-dimensional electron gas in piezoelectric scattering is of the order of 10-9 s.

A third route to synthesis of green phosphor SrSi2O2N2: Eu2+ from SrO

The green-emitting phosphor SrSi2O2N2: Eu2+, along with the cyan-emitting phosphor BaSi2O2N2: Eu2+, is a key component for phosphors used to package natural sunlight full-spectrum LED devices. Thereby, the synthesis of high-efficiency and thermal-stability luminous SrSi2O2N2: Eu2+ with an economic approach is very important for the development of LED industry. In this work, the syntheses of SrSi2O2N2: Eu2+ phosphors were optimized from four aspects: strontium sources, reaction atmospheres, reaction vessels, and reaction fluxes. Meanwhile, the relationship among photoluminescence performances, crystal structures, and morphologies were examined. The results show that the synthesis of SrSi2O2N2: Eu2+ from SrO and Sr(NO3)2 sources are beneficial to obtain N-rich oxynitide structure, which is helpful to improve luminescence. By employing SrCO3 and Sr(NO3)2 as strontium sources, however, the SrSi2O2N2: Eu2+ is O-rich and the by-product Sr2Si5N8:Eu is introduced. The optimal conditions for the synthesis of SrSi2O2N2: Eu2+ is by utilizing SrO as a strontium source, in N2 atmosphere, adopting Mo crucible, and adding NH4Cl as flux. The quantum yield of the optimal SrSi2O2N2: Eu2+ phosphor under the excitation of 380 nm reaches up to 100%.

Developing innovation capabilities for upgrading in global value chains: evidence from China

PurposeIn the face of fierce international competition for those participating in global value chains (GVCs), upgrading has been a central concern of emerging market firms (EMFs) that are trying to occupy higher value-added positions. However, although the innovation capabilities (ICs) have been generally considered critical to upgrading in GVCs, few studies have examined how IC is built up and then applied to the EMF upgrading process over time. To this end, the purpose of this paper is to investigate why and how EMFs can upgrade in GVCs through the development of their IC.Design/methodology/approachThis paper adopts a multiple-case study of three supplier firms in China and their IC development processes, with a special focus on the nature of the firm-level upgrading in GVCs.FindingsThe results generate a process model of EMFs upgrading with respect to the development of IC. The model reveals how IC is built up through the firms' underlying systematic innovation activities, which enable firms to successfully upgrade within GVCs. In particular, the role played by contextual vulnerability in guiding firms to develop the appropriate IC, and the corresponding upgrading, is highlighted.Research limitations/implicationsThis study contributes to the micro-foundation in GVCs literature, especially the traditional static upgrading research of EMFs. The authors also contribute to existing IC development research. Meanwhile, the study focuses on the upgrading of three Chinese firms in the phone and LED industries. The generalizability to other emerging markets and industries may therefore be limited.Practical implicationsThe study results show that EMFs could initially develop endogenous IC that focuses on process innovation as a means to establish a foundation for further upgrading. In addition, firms need to improve their ability to accurately sense contextual changes. As such, it would be valuable to understand their positions and characteristics within GVCs.Originality/valueThis paper investigates a process model of upgrading in GVCs through IC development in EMFs. This study also adds a dynamic micro-foundation to existing, rather macro and static GVCs studies.

The potential of far-UV for the next pandemic

According to the physicist Charlie Ironside, our ability to deal with future deadly pandemics could be better – if we look to the far-ultraviolet. Jon Cartwright reports on a call to arms for the LED industry

Implementing product platforms in the global enterprise: Lessons from an LED industry leader

Product platforming—using technology subsystems or components that are shared within and across product lines—is a proven way to increase the effectiveness of innovation processes in established companies and startups alike. Yet, embracing the product platforming strategy turns out to be difficult in practice, particularly within the context of global, diversified companies. In this article, we examine the strategies and challenges of implementing product platforms across multiple business segments and multiple geographies. Using the experience of global LED industry leader Signify, we explore the challenges of global platforming and the technological, organizational, management process transformations needed for success. We also examine how platforming strategies change as manufacturers enter the world of connected things.

What makes a successful industry-level catch-up? General framework and case study of China’s LED industry

How latecomers from emerging countries catch up on technological innovation is an important topic for industrial practitioners, policymakers, and academic researchers. This study systematically reviews 37 empirical studies on the precursors of industry catch-up in emerging countries. A general framework on what makes a successful catch-up in latecomer industries is suggested based on literature review. The framework comprises six generic determinants, including technological capability, business ecosystem, government roles, market condition, technological regime, and windows of opportunity. In addition, this framework is applied to the Chinese LED industry, and a case analysis of the catch-up is performed in Chinese LED firms.

Rely on the Industry's Leading Source for High-Reliability RF Cable Assemblies When Dependable Performance is Mission Critical

Rely on the Industry's Leading Source for High-Reliability RF Cable Assemblies When Dependable Performance is Mission Critical

(Invited) Ion Implantation and Activation of n- and p-Type Dopants in GaN

GaN-based power switching devices are of significant interest for high efficiency power conversion circuits in medium voltage applications. However, there are still significant challenges preventing mass production and widespread adoption. Recently, GaN-based vertical and lateral power devices have attracted significant interest due to promising device results coupled with progress in native substrate, epitaxial growth, and processing technology developments. However, there are two significant limiting factors for vertical GaN power devices at present. The first issue is substrate and epitaxial layer uniformity and reliability, and the second is the lack of a planar selective-area doping process. While p-type epitaxial growth capability and the ability to stack layers are quite mature from the LED industry, power devices require planar selective-area doping, which is a routine step by ion implantation in the Si and SiC device industry. The ability to implant and activate dopants, particularly p-type dopants, in GaN still remains a challenge as implant activation typically requires annealing at temperatures ~ 2/3 of the melting point, which is a region where the GaN crystal is unstable and readily decomposes to Ga + N2 at atmospheric pressure. The NRL-developed symmetric multicycle rapid thermal annealing (SMTRA) technique has been the most successful, demonstrating electrical activation of up to ~10% of the implanted Mg dopant atoms using a combination of a temporary, thermally stable capping layer, annealing in a moderate nitrogen overpressure, and performing a well-optimized annealing temperature profile including multiple spike anneals. Advances in the SMRTA process development, including optimization of capping processes, implantation profile, and processing steps such as metallization and surface treatments will be reviewed here. In addition, the evaluation of components of the SMRTA process, such as the cap and overpressure anneal, have been applied to Si implantation for n-type doping and will be presented here. This is a critical step to reduce contact resistance in lateral GaN structures as well as form the source regions of vertical devices that is typically accomplished by selective area regrowth. The use of ion implantation and activation utilizes fewer process steps and avoids impurity incorporation at sidewalls compared to the selective area regrowth process, and has been shown to yield lower contact resistance as well. This presentation will review advances in both Mg and Si ion implantation and assess the viability of this process for practical device fabrication.

How Do White LEDs’ Spectra Affect the Fresh Weight of Lettuce Grown under Artificial Lighting in a Plant Factory?—A Statistical Approach

Monochromatic light-emitting diode lamps (LEDs), emitting red and blue lights, revolutionized crop production in closed-system plant factories with artificial lighting in the early 1990s. The LED industry developed broad-spectrum white-LEDs by 2010, and many types of white-LEDs for home and office uses are now available for plant factory entrepreneurs. This paper tries to clarify whether these white-LEDs can be used as effective light sources in plant factories by examining what types of spectrum distribution are better suited for plant production. An experiment was conducted using seven LEDs, of which six were white-LEDs, to compare the performance in producing lettuce, and the results were compared with recent studies that used white-LEDs for growing lettuce under closed-system production conditions. Results showed that broad-spectrum white-LEDs performed significantly better than narrow-spectrum LEDs. Among lights in conventional color bands, red and blue lights give critical effects on plant growth, not in isolation but in combination; not too “cool” white LEDs perform better. Green and far-red lights also have some positive effects. Altogether, for a given light intensity, broad-spectrum white LEDs outperform narrow-spectrum LEDs. It is found that the spectrum distribution for white-LEDs to attain high productivity in lettuce production is such that the percentage share of photon flux density by conventional color band falls in the following ranges: 0% < blue < 30%, 0% < green < 50%, 30% < red < 70%, and 0% < far-red < 20%.

The philosophical views of national innovation system: The LED industry in Taiwan

Prior research on the national innovation system mostly emphasizes technological diffusion and industrial performance. The discipline of the national innovation system leads to extensive discussions of technological policy, strategic alliances, technological transfers, joint ventures, mergers and acquisitions, and even talent acquirements. However, little research has examined why and how the philosophical views of actors in a national innovation system (e.g. egoism, utilitarianism, and altruism) affect the industrial performance. This study draws on a qualitative, theory-building case study to examine the transforming LED industry in Taiwan and to renew and extend existing research on the national innovation system.

High-Stable Narrow Red Emitting Homogeneous K2SiF6:Mn4+@K2SiF6 Composite Phosphor for White LEDs: Green Synthesis and Water-Resistant Mechanism

Poor water resistance and non-green synthesis remain a great challenge for commercial narrow red emitting A2MF6:Mn4+ (A=alkali metal ion; M=Si, Ge, Ti) for solid state lighting and display. We develop here a simple and green growth route to synthesize homogeneous K2SiF6:Mn4+@K2SiF6 (KSFM@KSF) red emitting composite phosphor with excellent water resistance and high efficiency without the usage of toxic and volatile HF solution. After immersed into water for 6 hours, the as-obtained water-resistant products maintain 76% of the original emission intensity while the non-water-resistant ones steeply drop into 11%. Under 85% humidity and 85 oC for 504 h (21 days), the as-obtained water-resistant products remain 80-90%, much higher than 30-40% for the non-water-resistant products. Surface deactivation enabled growth mechanism was proposed, comprehensively investigated in detail. This composite structure strategy was also successfully used to treat KSFM prepared by other methods. We believe that it will open the opportunity for excellent anti-moisture narrow red emitting A2MF6:Mn4+ to be environment-friendly synthesized in large scale toward white LED industry adoptions.

Network characteristics and patent value-Evidence from the Light-Emitting Diode industry.

This study proposes a different angle to social network analysis that evaluates patent value and explores its influencing factors using the network centrality and network position. This study utilizes a logistic regression model to explore the relationships in the LED industry between patent value and network centrality as measured from out-degree centrality, in-degree centrality, in-closeness centrality, and network position, which is measured from effect size. The empirical result shows that out-degree centrality and in-degree centrality have significant positive effects on patent value and that effect size has a significant negative effect on patent value.

In-situ photoluminescence measurements during MOVPE of GaN and InGaN in a CCS reactor

Abstract Gallium Nitride (GaN) and Indium Gallium Nitride (InGaN) have become important semiconductor materials for the LED lighting industry. Recently, a photoluminescence (PL) technique for direct in-situ characterization of GaN and InGaN layers during epitaxial growth in a planetary metalorganic vapor phase epitaxy (MOVPE) reactor was reported. The PL signals reveal – at the earliest possible stage – information about current layer thickness, temperature, composition, surface roughness, and self-absorption. Thus, the PL data is valuable for both controlling and optimizing the growth parameters, thereby promising both better devices and a better yield for the LED industry. This technical report describes an extension of this PL technique to close coupled showerhead (CCS) reactors with narrow optical viewports. In contrast to the wide aperture optics in previous investigations, a compact and all-fiber optical probe without voluminous lens optics, filter elements or beam splitters was used.