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Epitaxial growth of III-V materials on a CMOS-compatible Si (001) substrate enables the feasibility of mass production of low-cost and high-yield Si-based III-V optoelectronic devices. However, the material dissimilarities between III-V and group-IV materials induce several types of defects, especially threading dislocations (TDs) and antiphase boundaries (APBs). The presence of these defects is detrimental to the optoelectronic device performance and thus needs to be eliminated. In this paper, the mechanism of APB annihilation during the growth of GaAs on on-axis Si (001) is clarified, along with a detailed investigation of the interaction between TDs and the periodic {110} APBs. A significant reduction in the TD density ascribed to the presence of periodic APBs is discussed. This new observation opens the possibility of reducing both APBs and TDs simultaneously by utilising optimised GaAs growth methods in the future. Hence, a thin APB-free GaAs/Si (001) platform with a low TD density (TDD) was obtained. Based on this platform, a high-performance high-yield III-V optoelectronic device grown on CMOS-compatible Si (001) substrates with an overall thickness below the cracking threshold is feasible, enabling the mass production of Si-based photonic integrated circuits (PICs).

The Chungcheongbuk-do Agricultural Research and Extension Service has developed a new intergenic hybrid orchid cultivar released under the name ‘Pinky Beauty.’ The marketable qualities of this new cultivar include an abundance of flowers, a good fragrance, and a relatively long flowering period. It was derived from an initial intergeneric cross between (Phalaenopsis pulcherrima x P. parishii ) x Neofinetia falcata ‘Hwacheon’ in 2007. The seed germination, cultivation, selection, and characteristic evaluation trials were conducted from 2008 to 2014. After selecting a line that grew well and had desirably shaped and colored flowers, its morphological characteristics were investigated, from 2015 to 2017, according to the survey standard for agricultural experimentation and research that is used for the evaluation of new N. falcata varieties. The selection had pink flowers, which were determined to be Red-purple Group 68D based on the RHS color chart, on a dark green stem. The length of the flower stem was measured on average to be 25.8 cm, and the number of flowers per stem was 16.3. The width of a typical flower was about 2.5 cm, and the flowers had a short spur similar to N. falcata on the back of the lip. The plant height was on average 12.7 cm, which is similar to the control cultivar P. pulcherrima, while the leaf width was 1.6 cm. The overall volume of the flower pot was high. The flowering time of the hybrid was in late May, and its flowering period was about 34 days. Furthermore, it had a noticeably pleasant scent. Due to this desirable combination of characteristics, the selection was released as the cultivar ‘Pinky Beauty’ in 2018.

Development of Si photonic integrated circuits (PICs) has been impeded due to lack of efficient Si-based light-emitting sources. Because of their indirect bandgap, bulk Ge and Si are very inefficient at emitting light. Therefore, direct-bandgap III-V semiconductors have been extensively exploited for the active region of the lasers for PICs. Heterogeneous and monolithic integration of III-V semiconductor components on Si platforms have been considered as promising solutions to achieve practical on-chip light-emitting sources for Si photonics. This paper reviews the latest developments on telecommunication wavelength III-V lasers integrated on Si substrates, in terms of integration methods and laser performance.

In this work, we investigate the epitaxial growth of InAs quantum dots (QDs) on Ge substrates. By varying the growth parameters of growth temperature, deposition thickness and the growth rate of InAs, high density (1.2 × 1011 cm−2) self-assembled InAs QDs were successfully epitaxially grown on Ge substrates by solid-source molecular beam epitaxy and capped by Ge layers. Pyramid- and polyhedral-shaped InAs QDs embedded in Ge matrices were revealed, which are distinct from the lens- or truncated pyramid-shaped dots in InAs/GaAs or InAs/Si systems. Moreover, with a 200 nm Ge capping layer, one-third of the embedded QDs are found with elliptical and hexagonal nanovoids with sizes of 7–9 nm, which, to the best of our knowledge, is observed for the first time for InAs QDs embedded in a Ge matrix. These results provide a new possibility of integrating InAs QD devices on group-IV platforms for Si photonics.

We investigated the optical feedback effects on the static and dynamic characteristics of 1.3 μm quantum-dot (QD) Fabry–Pérot laser under reflection from −40 dB up to −8 dB. The onset of coherence collapse is determined as −14 dB from the optical and electrical spectra. Although the degradation in small signal modulation is reported above this critical feedback level, transmission operation with available eye diagram under higher feedback is demonstrated. Under 10 Gb s−1 modulation, there is no obvious degradation in eye diagram regarding the eye shape and extinction ratio up to feedback ratio of −8 dB. The higher feedback tolerance of QD laser under large signal modulation is attributed to the impact of gain compression. This high-speed feedback-resistant operation also indicates that QD laser is a promising light source for isolator-free photonic integrated circuits.

Monolithic Si-based light sources have long been pursued for Si photonics. However, Si is a very inefficient light-emitting material because of its indirect bandgap. Monolithic growth of III–V materials on Si has been regarded as a promising approach due to their superior optical and electrical properties. Nonetheless, the deployment of monolithic III–V lasers on photonic integrated circuits is still hampered by the high density of various defects during the crystal growth. For several reasons, the use of III–V quantum dots (QDs) as an active region offers substantial advantages including tolerance to defects, low threshold current density, and temperature-insensitive operation because of the unique confinement characteristic of QDs. Accordingly, a great deal of effort has been made to demonstrate the operation of monolithic III–V QD lasers on Si. This chapter reviews the recent advances of monolithic III–V QD lasers on Si and, discusses the current challenges and future directions.

Monolithic integration of III–V materials and devices on CMOS compatible on‐axis Si (001) substrates enables a route of low‐cost and high‐density Si‐based photonic integrated circuits. Inversion boundaries (IBs) are defects that arise from the interface between III–V materials and Si, which makes it almost impossible to produce high‐quality III–V devices on Si. In this paper, a novel technique to achieve IB‐free GaAs monolithically grown on on‐axis Si (001) substrates by realizing the alternating straight and meandering single atomic steps on Si surface has been demonstrated without the use of double Si atomic steps, which was previously believed to be the key for IB‐free III–V growth on Si. The periodic straight and meandering single atomic steps on Si surface are results of high‐temperature annealing of Si buffer layer. Furthermore, an electronically pumped quantum‐dot laser has been demonstrated on this IB‐free GaAs/Si platform with a maximum operating temperature of 120 °C. These results can be a major step towards monolithic integration of III–V materials and devices with the mature CMOS technology.

In this study, the seismic performance and inelastic behavior of joints were investigated using the bracket thickness, depth, and stiffener of the ceiling-bracket-type modular system as parameters. The performances of the joints were evaluated through a cyclic loading test and the nonlinear FEA. The initial stiffness, maximum flexural strength, failure mode at the ultimate stage, energy dissipation capacity, and inelastic behavior were analyzed, and it was determined whether the strong-column/weak-beam-type mechanism occurs at the joint. The results of the analysis were compared with those of the theoretical and FE models, respectively. For the comparison of the seismic performances, the flexural strength of the joint at the 0.04 and 0.05 rad inter-story drift ratios, which exceed the plastic moment, was investigated. From the comparison results, the standard specimen had a sufficient structural performance compared to the reference model, which was a welded joint. The joint was shown to be capable of maintaining a seismic performance higher than 80% of the plastic moment, and showed strain curves pointing to a strong column-weak beam behavior. In the joints, the initial stiffness was increased with a higher bracket thickness. In addition, the maximum flexural strength showed a large change in the loading direction due to the ceiling bracket. If the number of stiffeners is reduced, the joint will have both reduced initial stiffness and reduced maximum flexural strength. The bracket-type modular building was shown to be an effective and dependable modular system for resisting seismic loads, and the energy dissipation capacity of the standard specimen was shown to be higher than those of the other modular joints

Next-generation sequencing (NGS)-based studies have reported a large amount of transcriptome data. In fact, plant transcriptome data sometimes contain sequence reads associated with viruses and viroids. Recently, we screened several grapevine transcriptomes to identify viruses and viroids that infect grapevine and we selected a transcriptome of the grapevine cultivar Cabernet Sauvignon for an in silico data analysis. After de novo assembly of raw data, the obtained contigs were blasted against a virus reference database. We identified five viruses and two viroids that infected the grapevine. We discovered that 2.16% of the transcriptome was comprised of viral RNAs, with more than half of the viral reads deriving from grapevine rupestris stem pitting-associated virus. However, the RNA populations of the two viroids were more than half of the total viral population based on the viral RNA copy number. Moreover, we identified single nucleotide polymorphisms for each virus and viroid and performed phylogenetic analyses. Taken together, we report the successful application of plant transcriptome data using bioinformatics analyses in the identification of five viruses and two viroids in the grapevine cultivar Cabernet Sauvignon, which is one of the most important grapevine cultivars in the world.

Polymer/metal/polymer and polymer/metal/inorganic trilayer-structured transparent electrodes with fluorocarbon plasma polymer thin film heaters have been proposed. The polymer/metal/polymer and polymer/metal/inorganic transparent conducting thin films fabricated on a large-area flexible polymer substrate using a continuous roll-to-roll sputtering process show excellent electrical properties and visible-light transmittance. They also exhibit water-repelling surfaces to prevent wetting and to remove contamination. In addition, the adoption of a fluorocarbon/metal/fluorocarbon film permits an outer bending radius as small as 3 mm. These films have a sheet resistance of less than 5 Ω sq–1, sufficient to drive light-emitting diode circuits. The thin film heater with the fluorocarbon/Ag/SiNx structure exhibits excellent heating characteristics, with a temperature reaching 180 °C under the driving voltage of 13 V. Therefore, the proposed polymer/metal/polymer and polymer/metal/inorganic transparent conducting el...

We developed hybrid Ag nanodots (NDs)/Ag nanowires (NWs) electrodes for enhancing the light output power of near ultraviolet (NUV) AlGaN-based light-emitting diodes (LEDs). At 385 nm, 10-nm-thick ITO-only films deposited on p-GaN/sapphire gave a transmittance of 70%, whereas hybrid Ag NDs/Ag NWs film showed a transmittance of 47%. LEDs with ITO-only, Ag NDs/Ag NWs, and activated-Ag NDs/Ag NWs electrodes showed forward-bias voltages of 3.50, 3.65, and 3.57 V, respectively, at 20 mA. The LEDs with the ITO-only, Ag NDs/Ag NWs, and activated-Ag NDs/Ag NWs electrodes produced series resistances of 14.3, 15.2, and 14.5 Ω, respectively. The LEDs with the Ag NDs/Ag NWs and activated-Ag NDs/Ag NWs electrodes yielded 13.1% and 23.7% higher light output powers, respectively, at 20 mA than that produced with the ITO-only electrode. On the basis of the emission images obtained from the LEDs with 10-nm-thick ITO-only, Ag NDs/Ag NWs, and activated-Ag NDs/Ag NWs electrodes, the enhanced light output power is attributed to effective current spreading and current injection.

We developed NiZn/(Ta/)Ni ohmic contacts to replace expensive AuBe/Au contacts commonly used in high-efficiency AlGaInP-based light-emitting diodes (LEDs), and compared the electrical properties of the two contact types. Unlike the AuBe/Au (130 nm/100 nm) contact, the NiZn/Ta/Ni (130 nm/20 nm/100 nm) contact shows improved electrical properties after being annealed at 500°C, with a contact resistivity of 5.2 × 10−6 Ω cm2. LEDs with the NiZn/Ta/Ni contact exhibited a 4.4% higher output power (at 250 mW) than LEDs with the AuBe/Au contact. In contrast to the trend for the AuBe/Au contact, the Ga 2p core level for the NiZn/Ta/Ni contact shifted toward lower binding energies after being annealed at 500°C. Auger electron spectroscopy (AES) depth profiles showed that annealing the AuBe/Au samples caused the outdiffusion of both Be and P atoms into the metal contact, whereas in the NiZn/Ta/Ni samples, Zn atoms indiffused into the GaP layer. The annealing-induced electrical degradation and ohmic contact formation mechanisms are described and discussed on the basis of the results of x-ray photoemission spectroscopy and AES.

© 1983-2012 IEEE. High-performance III-V quantum-dot lasers monolithically grown on Si substrates have been demonstrated as a promising solution to realize Si-based laser sources with very low threshold current density, high output power, and long lifetime, even with relatively high density of defects due to the material dissimilarities between III-Vs and Si. On the other hand, although conventional III-V quantum-well lasers grown on Si have been demonstrated after great efforts worldwide for more than 40 years, their practicality is still a great challenge because of their very high threshold current density and very short lifetime. However, the physical mechanisms behind the superior performance of silicon-based III-V quantum-dot lasers remain unclear. In this paper, we directly compare the performance of a quantum-well and a quantum-dot laser monolithically grown on on-axis Si (001) substrates, both experimentally and theoretically, under the impact of the same density of threading dislocations. A quantum-dot laser grown on a Si substrate with a high operating temperature (105 °C) has been demonstrated with a low threshold current density of 173 A/cm2 and a high single facet output power >100 mW at room temperature, while there is no lasing operation for the quantum-well device at room temperature even at high injection levels. By using a rate equation travelling-wave model, the quantum-dot laser's superior performance compared with its quantum well-based counterpart on Si is theoretically explained in terms of the unique properties of quantum dots, i.e., efficient carrier capture and high thermal energy barriers preventing the carriers from migrating into defect states.

We propose a new method of fabricating metal&ndash, polymer composite targets for sputtering, which makes it easier to control the composition and enables the homogeneous and reproducible fabrication of metal&ndash, polymer nanocomposites over large areas. Using Cu/polytetrafluoroethylene composite targets containing 20, 50, and 80 wt.% Cu, Cu/plasma polymer fluorocarbon (PPFC) nanocomposite thin films were prepared by radio-frequency (RF) sputtering. Targets with 80 wt.% Cu were conductive, moreover, sputtering was possible not only with RF but also with mid-range frequency (MF) and direct current (DC) power sources. The nanocomposite thin film deposited by MF and DC power using an 80 wt.% Cu target showed near-metallic characteristics, exhibited absorption peaks at 618 and 678 nm, and had a surface resistance of 2 &times, 104 and 34.55 &Omega, /sq, respectively. We also analyzed the structure and composition of the Cu/PPFC nanocomposite films by X-ray diffraction and X-ray photoelectron spectroscopy. The described metal&ndash, polymer targets can advance the applications and commercialization of nanocomposite thin films.

In this study, we introduced mesh-patterned Ag grid (width: 1520m) to enhance the light output power of near ultraviolet (385nm) AlGaN-based light emitting diode (LEDs). The Ag grid was intentionally agglomerated by annealing at 500C for 1min in air. The output performance of AlGaN-based LEDs fabricated with Ag-grid/indium tin oxide (ITO) electrodes was compared with those with ITO electrode. At a wavelength of 385nm, the samples had transmittances of 54.274.1%. LEDs with the Ag-grid/ITO contacts exhibited lower forward voltages of 3.323.57V at 20mA than LED with the ITO electrode (3.64V). The LEDs with the Ag-grid/ITO electrodes exhibited 15.615.9% higher light output (at 400mW) than that with the ITO electrode. Based on finite-difference time-domain simulations, the improved output performance is briefly described and discussed. Display Omitted Agglomerated Ag grid used to improve the light output power of AlGaN-based LEDs.Agglomerated Ag grid samples had transmittances of 54.274.1% at 385nm.LEDs with Ag grid show much lower forward voltages than LEDs with ITO contact.LEDs with Ag grid yield higher output power than LEDs with ITO electrode

This study was conducted to investigate the weed occurrence and distribution on the orchard fields (apple, pear, peach, grape) at 387 sites in Chungbuk province of Korea from May to September in 2015. From the result of this survey, 200 weed species in 47 families were identified and classified to 82 annuals, 40 biennials and 78 perennials. Based on the occurrence ratio, the most dominant weed species in Chungbuk province orchard fields were higher in order of Digitaria ciliaris (4.12%), Echinochloa crus-galli (3.60%), Stellaria aquatica (3.45%), Artemisia princeps (3.07%) and Chenopodium album (3.06%). The composition of major occurred weed families, Compositae, Poaceae, Leguminosae and Cyperaceae were 21, 9, 6 and 6%, respectively. Coefficient of similarity between a various orchards based on the degree of dominance were ranged from 68.7-91.8%. The most important weed species at apple, peach, grape was Digitaria ciliaris while these for pear was Poa annua. Fifty-one exotic weed species were also identified. The results of this study could be useful information for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods on the orchard fields in Chungbuk province of Korea.

Ag nanowires (Ag NWs) were combined with a thin indium tin oxide (ITO) film as the p-type electrode in near ultraviolet (NUV) AlGaN-based light-emitting diodes (LEDs) to improve the light output power. The Ag NWs (30 ± 5 nm in diameter and 25 ± 5 μm long) were dispersed in ethanol (0.3 wt%). The transmittances of 10 nm-thick ITO, ITO/Ag NWs coated at 1000 rpm, and ITO/Ag NWs coated at 3000 rpm were 98%, 90%, and 97% at 385 nm, respectively. LEDs (chip size: 300 × 800 μm2) fabricated with the ITO/Ag NW electrode exhibited higher forward-bias voltages than the LEDs with the ITO-only electrode. However, LEDs with ITO/Ag NWs films coated at 1000 and 3000 rpm yielded 7.9 and 14.0% higher light output power, respectively, at 100 mA than the LED with ITO-only electrode. The improved output power with the ITO/Ag NWs films is attributed to an optimal trade-off between optical transmittance and current spreading.

We investigated how a tungsten diffusion barrier layer affected the electrical properties of AuBe/Au contacts to a p-GaP window layer (na = 5 × 1019 cm−3) for an AlGaInP-based light emitting diode. All of the as-deposited samples were ohmic. After annealing at 500 °C, the AuBe/Au contacts were electrically degraded with a specific contact resistivity of 1.0 × 10−4 Ωcm2. However, the electrical properties of the W-based contacts were improved, having a contact resistivity of 5.0 × 10−6 Ωcm2. The X-ray photoemission spectroscopy (XPS) results showed that the Ga 2p core level for the annealed AuBe/Au contacts shifted to the high binding-energy side. On the other hand, that for the AuBe/W/Au contacts shifted toward the lower binding-energy side. For the AuBe/Au contacts, both Be and P atoms were shown to be outdiffused into the metal contact after annealing. However, for the AuBe/W/Au contacts, the outdiffusion of Be atoms was prevented by the W barrier layer, and the Be atoms were indiffused into GaP. Based on the X-ray photoemission spectroscopy (XPS), Auger electron spectroscopy (AES), and electrical results, the annealing-induced electrical degradation and improvement are described and discussed.

The electrical properties of Ti/Al-based ohmic contacts to (0001) c-plane and (11–22) semipolar n-type GaN were investigated as a function of annealing temperature. The electrical properties of both c-plane Ti/Al/Au and semi-polar Ti/(Ta)/Al/Au contacts became improved upon annealing at 600 °C for 1 min. The specific contact resistances of the 600 °C-annealed c-plane Ti/Al/Au, semi-polar Ti/Al/Au, and semipolar Ti/Ta/Al/Au contacts were 3.2 × 10 −4 , 1.5 × 10 −4 , and 4.8 × 10 −5 Ωcm 2 , respectively. The X-ray photoemission spectroscopy (XPS) results showed that the Ga 2p core level for the c-plane samples experienced a smaller shift toward the conduction band than that for the semipolar samples. The XPS depth profile results exhibited that the semipolar samples contained more interfacial oxygen than the c-plane samples. Oxygen was present in the form of Al-oxide at the interface region, but as oxygen atoms in the GaN surface region. On the basis of the electrical and XPS results, the annealing-induced improvement of the electrical properties was described in terms of the formation of donor-like defects.

GaN-based light-emitting diodes (LEDs) fabricated with Ag particles embedded within a SiO 2 current blocking layer (CBL) are demonstrated. The Ag particles varied from 100 to 250 nm in size, and had a density of ∼3.8 × 10 8 cm −2 . The transmittances obtained from GaN/sapphire and Ag particles/GaN/sapphire were 75 and 66% at 450 nm, respectively. The LEDs (chip size: 1000 × 1000 μm 2 ) fabricated with ITO-only, ITO/SiO 2 CBL, and ITO/Ag particles/SiO 2 CBL showed forward-bias voltages of 3.05, 3.25 and 3.1 V at 20 mA, respectively. The LEDs with the ITO/Ag particles/SiO 2 CBL yielded 11.9 and 7.0% higher light output powers (at 20 mA) than the LEDs with the ITO-only and ITO/SiO 2 CBL, respectively. The improved output power is explained by the combined effects of the improved extraction and current spreading.

Here, we report the genome sequence of grapevine virus K (GVK), a novel single-stranded RNA virus identified from a transcriptome of grapevine. The genome of GVK is 7,476 nucleotides in length and encodes 5 open reading frames. GVK is a putative member of the genus Vitivirus in the family Betaflexiviridae .

Modular systems have been mostly researched in relatively low-rise structures but, lately, their applications to mid- to high-rise structures began to be reviewed, and research interest in new modularization subjects has increased. The application of modular systems to mid- to high-rise structures requires the structural stability of the frame and connections that consist of units, and the evaluation of the stiffness of structures that are combined in units. However, the combination of general units causes loss of the cross-section of columns or beams, resulting in low seismic performance and hindering installation works in the field. In addition, the evaluation of a frame considering such a cross-sectional loss is not easy. Therefore, it is necessary to develop a joint that is stable and easy to install. In the study, a rigidly connected modular system was proposed as a moment-resisting frame for a unit modular system, and their joints were developed and their performances were compared. The proposed system changed the ceiling beam into a bracket type to fasten bolts. It can be merged with other seismic force-resisting systems. To verify the seismic performance of the proposed system, a cyclic loading test was conducted, and the rigidly connected joint performance and integrated behavior at the joint of modular units were investigated. From the experimental results, the maximum resisting force of the proposed connection exceeded the theoretical parameters, indicating that a rigid joint structural performance could be secured.

Low-resistance Ag ohmic contacts to semi-polar (1 1 −2 2) p-GaN were developed by controlling interfacial oxide using a Zn layer. The 300 °C-annealed Zn/Ag samples showed ohmic behavior with a contact resistivity of 6.0 × 10−4 Ω cm2 better than that of Ag-only contacts (1.0 × 10−3 Ω cm2). The X-ray photoemission spectroscopy (XPS) results showed that annealing caused the indiffusion of oxygen at the contact/GaN interface, resulting in the formation of different types of interfacial oxides, viz. Ga-oxide and Ga-doped ZnO. Based on the XPS and electrical results, the possible mechanisms underlying the improved electrical properties of the Zn/Ag samples are discussed.

The survey of weed occurrence was conducted to identify dominant weed species in the paddy field. Total 346 sites of the 12 regions in Chungbuk Province in Korea were investigated in July, 2013. Weed flora was composed of 43 species belonged to 15 families. The compositions of major plant families, Cyperaces, Poaceae, Pontederiaceae and Asteraceae, were 21.5, 17.4, 15.5 and 12.7%, respectively. Based on life cycle, weed species was grouped into annuals of 71.3 and perennials of 28.1%. The most dominant weed species in paddy fields of Chungbuk Province were Monochoria vaginalis (14.5%), followed by Scirpus juncoides (10.5%), Echinochloa oryzoides (9.3%), Eleocharis kuroguwai (7.0%), Aeschynomene indica (6.2%) et al. The similarity of paddy weeds in 12 regions observed through TWINSPAN analysis was distinguished by Persicaria longiseta, Aneilema keisak, Persicaria thunbergii, Fimbristylis millacea, Blyxa japonica, Digitaria ciliaris, Potamogeton distinctus, Cyperus nipponicus. This information could be useful for estimation of future weed occurrence and establishment of weed control methods in chungbuk province in Korea.

A program that predicts trajectories of projectiles influenced by the interference flow field of helicopters is developed. The interference flow field are computed using a compressible inviscid solver in conjunction with an actuator disc model. The trajectories are predicted using 6-DOF (Degree of Freedom) equations as well as an alternative form of modified point mass equations of motion. The method for the interference flow field prediction method are validated with ROBIN(ROtor Body INteraction) model. A Sierra international bullet and a 105mm projectile are used to validate the trajectory method. Trajectories of a Sierra International bullet and a HYDRA 70 rocket firing from a helicopter are predicted.

Pd/Zn/Ag ohmic contacts to Ga-face p-type GaN were investigated as a function of annealing temperature. The Pd/Zn/Ag ohmic contacts exhibited a reflectance of 85% at 450 nm, which is higher than that of Ag-only contacts (57%) after annealing at 500 °C. The alleviated agglomeration of the Pd/Zn/Ag ohmic contact due to the formation of ZnO at the surface seems to be responsible for the higher reflectance. The specific contact resistances of Ag-only and Pd/Zn/Ag contacts annealed at 500 °C were 2.4 × 10−4 and 6.1 × 10−5 Ω cm2, respectively. GaN-based light-emitting diodes (LEDs) fabricated with the Pd/Zn/Ag contacts exhibited ∼20% higher output power at 20 mA than the LEDs fabricated with the Ag-only contacts annealed at 500 °C. On the basis of X-ray photoemission spectroscopy and SEM results, the improved electrical and thermal properties are described.

We report on the improved performance of near-ultraviolet (385 nm) InGaN/GaN multi-quantum well light emitting diodes (LEDs) by enhancing the thermal and electrical properties of Ag-based reflector. It is shown that after annealing at 500 °C, indium (In)-overlaid Ag contact exhibits considerably higher reflectivity at 385 nm than Ag only contact. After annealing at 500 °C, both the Ag only and In-overlaid Ag contacts are ohmic with a specific contact resistance of 6.7 × 10 −4 and 8.7 × 10 −5 Ω cm 2 , respectively. Near-UV (385 nm) LEDs fabricated with annealed Ag only and In-overlaid Ag reflectors show a forward-bias voltage of 3.4 and 3.37 V at an injection current of 20 mA, respectively. The LEDs with the annealed In-overlaid Ag reflector exhibit 24.7% higher light output power (at 20 mA) than the LEDs with the 500 °C-annealed Ag only reflector. X-ray photoemission spectroscopy was performed to understand the improved electrical properties of the In-overlaid Ag reflectors. The enhanced thermal stability of In-overlaid Ag reflector is also briefly described.

The purpose of the present study was to develop a convergent education contents for dementia prevention, operating on the web network applying modern information technology(IT). At the preparation stage, local and worldwide literatures related to dementia were analyzed followed by surveying industry demands, based on which the program was designed and developed. In the following enhancement stage, the program was modified as much as possible by advices obtained from experts in various fields. Development results of the present program are summarized as follows. Firstly, 645 intellect development model to prevent dementia was established through peer review and verification of convergent education theories by expert groups. This model was named as "Garisani" meaning "cognition capable of judging objects" in the Korean language. Secondly, `Find a way` and `Connect a line` modules were developed in the numeric field as well as `Identify a letter(I, II)` modules, in the language field for web-based left brain training program. Thirdly, `Find my car` and `Vision training` modules in the attention field and `Object inference` and `Compare pictures` modules in the cognition field were developed for web-based right brain training program. Fourth, `Pentomino` and `BQmaze`(Brain Quotient and maze) modules in the space perception field and `Visual training` in the memory field were developed for web-based left and right brains training. Fifth, all results were integrated leading to a 52 week Garisani convergent education program for dementia prevention.

We investigate the agglomeration behavior of Ag films on GaN as functions of thickness and temperature. The SEM results show that the thinner films become agglomerated at temperatures below 500 °C, whereas the thicker films (⩾700 nm) remain stable with hillocks at 500 °C, (although the density of small holes depends on their thickness). The holes that are formed adjacent to the hillocks lead to the initiation of agglomeration. The X-ray texture analyses exhibit that although the majority of grains are 〈1 1 1〉-oriented, a fraction of them are 〈1 0 0〉-textured when deposited on GaN. For the samples thicker than 700 nm, amount of the 〈1 0 0〉-textured grains increases with increasing temperature, but this is not the case for the samples thinner than 500 nm. The SEM and X-ray pole figure results exhibit that a decrease in the I{2 0 0}/I{1 1 1} pole figure intensity ratios is related to the growth of holes, leading to agglomeration. Based on the SEM and X-ray texture results, the thickness dependence of the texturing and agglomeration behavior of Ag films are described and discussed.

Silver (Ag) contacts are important reflectors for vertical-structure GaN-based light-emitting diodes (LEDs). The Ag contacts produce good electrical and optical properties at different annealing temperatures. Thus, in order to best optimize the reliability of LEDs, we introduced an Ag activation process before performing normal annealing treatments. In other words, after removing 200-nm-thick Ag layers on p-GaN that were annealed at 500 °C for 1 min, Ag films were deposited on the Ag-activated p-GaN, which were subsequently annealed at 300 °C for 1 min. The activated LEDs fabricated with the 300 °C-annealed Ag contacts reveal better electrical properties than the reference LEDs. For example, the activated LEDs give a forward voltage of 2.92 V at an injection current of 20 mA, whereas the reference LEDs with the 300- and 500 °C-annealed Ag contacts yield 3.02 and 2.98 V at 20 mA, respectively. The activated LEDs yield 4.9% and 17% higher output power (at 30 mW) than the reference LEDs with the Ag contacts annealed at 300 and 500 °C. The activation-induced electrical improvement is briefly described and discussed.

The purpose of this study is to be conducive to work improvement through analyzing turnover intention and organizational commitment of EMT within medical institution. The subjects of this study were randomly extracted 188 EMT. The survey period was conducted from May 3, 2011 to May 19 (May 3rd-4th in G Province, May 14th in B Metropolitan City, May 18th-19th in D Metropolitan City). An analytical method was made with SPSS WIN program(Version 12.0). As a result of research, the turnover intention was high in women(p

Indium tin oxide (ITO) nanodots (NDs) were combined with Ag nanowires (Ag NWs) as a p-type electrode in near ultraviolet AlGaN-based light-emitting diodes (LEDs) to increase light output power. The Ag NWs were 30 ± 5 nm in diameter and 25 ± 5 μm in length. The transmittance of 10 nm-thick ITO-only was 98% at 385 nm, while the values for ITO ND/Ag NW were 83%–88%. ITO ND/Ag NW films showed lower sheet resistances (32–51 Ω sq−1) than the ITO-only film (950 Ω sq−1). LEDs (chip size: 300 × 800 μm2) fabricated using the ITO NDs/Ag NW electrodes exhibited higher forward-bias voltages (3.52–3.75 V at 20 mA) than the LEDs with the 10 nm-thick ITO-only electrode (3.5 V). The LEDs with ITO ND/Ag NW electrodes yielded a 24%–62% higher light output power (at 20 mA) than those with the 10 nm-thick ITO-only electrode. Furthermore, finite-difference time-domain (FDTD) simulations were performed to investigate the extraction efficiency. Based on the emission images and FDTD simulations, the enhanced light output with the ITO ND/Ag NW electrodes is attributed to improved current spreading and better extraction efficiency.

A Ru capping layer is employed to improve the thermal stability of Ag ohmic reflectors for high-power GaN-based light-emitting diodes (LEDs). The 20-nm-thick Ru capping layer is shown to be fairly effective in suppressing agglomeration by forming RuO 2 . The Ag/Ru contacts exhibit specific contact resistance of 8.1 × 10 −5 Ω cm 2 and reflectance of ∼89% at a wavelength of 450 nm when annealed at 500 °C for 1 min, which are much better than that of Ag only contacts. Blue LEDs fabricated with the 500 °C-annealed Ag/Ru contacts give a forward voltage of 2.98 V at an injection current of 20 mA, which is lower than that (3.02 V) of LEDs with the 500 °C-annealed Ag only contacts. LEDs with the 500 °C-annealed Ag/Ru contacts show 25% higher output power (at 20 mA) than LEDs with the 500 °C-annealed Ag only contacts. X-ray photoemission spectroscopy examinations are performed to describe the improved electrical performance of the Ag/Ru contacts.