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The effect of solidification rate on micro-segregation in investment casting of IN738LC superalloy was studied. In Ni-based superalloys, the micro-segregation of solute atoms is formed due to limited diffusion during cast and solidification. The microstructure of cast Ni-based superalloys is largely divided into dendrite core of initial solidification and interdendrite of final solidification. In particular, mosaic shaped eutectic γ/γ’ and carbides are formed in the interdendrite of the final solidification region in some cases. The micro-segregation phenomena formed in regions of dendrite core and interdendrite including eutectic γ/γ’ and carbides were analyzed using OM, SEM/EDS and micro Vickers hardness. As a result of analysis, the lack of (Cr, W) and the accumulation of Ti were measured in the eutectic γ/γ’, and the accumulation of (Cr, Mo) and the lack of Ti were measured in the interdendrite between dendrite and eutectic. Carbides formed in interdendritic region were composed of (Ti, W, Mo, C). The segregation applied to each microstructure is mainly due to the formation of γ’ with Ni3(Al,Ti) composition. The Ni accumulation accompanied by Cr depletion, and the Ti accumulated in the eutectic region as a γ’ forming elements. The Mo tends to diffuse out from the dendrite core to the interdendrite, and the W diffuse out from the interdendrite to the dendrite core. Therefore, the accumulation of Mo in the interdendrite and the deficiency of W occur in the eutectic region located in the interdendrite. Heat treatment makes the degree of the micro-segregation decrease due to the diffusion during solid solution. This study could be applied to the heat treatment technology for the micro-segregation control in cast Ni-based superalloys.

Herein we describe theoretical and experimental analysis of the source resistance (Rs) components in In0.7Ga0.3As/In0.52Al0.48As quantum-well (QW) high-electron-mobility transistors (HEMTs) on an InP substrate. First, we analytically modeled Rs using a three-layer formula, separately modeling the regions of the ohmic contact, the gate-to-source access, and the side-recessed regions. The resistances of the ohmic contact and access regions were analyzed in a distributed-network manner with two different transfer lengths, whereas the resistance associated with the side-recess region near the gate edge was modeled by using a lumped element. To verify the accuracy of the proposed Rs model, we fabricated two different types of transmission-line-method (TLM) test patterns as well as long-channel In0.7Ga0.3As/In0.52Al0.48As QW HEMTs, and compared their measured and modeled Rs. The modeled Rs was in excellent agreement with the measured Rs from the recessed TLM patterns and the long-channel HEMTs. Since the widths of the ohmic contact to the heavily doped In0.53Ga0.47As capping layer and the gate-to-source access region were typically much greater than corresponding transfer lengths ( $$L_{{{\text{T}}\_{\text{cap}}}}$$ and $$L_{{{\text{T}}\_{\text{barrier}}}}$$ ), those distributed networks could be simplified to a lumped-element based one-layer model, revealing that the tunneling resistance ( $$R_{{{\text{barrier}}}}$$ ) through the In0.52Al0.48As barrier should be carefully considered to minimize the Rs of InxGa1−xAs QW HEMTs together with S/D contact resistances and LGS.

We report facile growth methods for high-quality monolayer and multilayer MoS2 films using MoOCl4 as the vapor-phase molecular Mo precursor. Compared to the conventional covalent solid-type Mo precursors, the growth pressure of MoOCl4 can be precisely controlled. This enables the selection of growth mode by adjusting growth pressure, which facilitates the control of the growth behavior as the growth termination at a monolayer or as the continuous growth to a multilayer. In addition, the use of carbon-free precursors eliminates concerns about carbon contamination in the produced MoS2 films. Systematic studies for unveiling the growth mechanism proved two growth modes, which are predominantly the physisorption and chemisorption of MoOCl4. Consequently, the thickness of MoS2 can be controlled by our method as the application demands.

We investigated the impact of a sulfur passivation (S-passivation) process step on carrier transport properties of surface-channel In0.7Ga0.3As quantum-well (QW) Metal-Oxide-Semiconductor Field-Effect-Transistors (MOSFETs) with source/drain (S/D) regrowth contacts. To do so, we fabricated long-channel In0.7Ga0.3As QW MOSFETs with and without (NH4)2S treatment prior to a deposition of Al2O3/HfO2 = 1-nm/3-nm by atomic-layer-deposition (ALD). The devices with S-passivation exhibited a lower value of subthreshold-swing (S) = 74 mV/decade and more positive shift in the threshold voltage ( $\text{V}_{\mathrm{ T}}$ ) than those without S-passivation. From the perspective of carrier transport, S-passivated devices displayed excellent effective mobility ( $\mu _{eff}$ ) in excess of 6,300 cm2/ $\text{V}\cdot \text{s}$ at 300 K. It turned out that the improvement of $\mu _{eff}$ was attributed to reduced Coulombic and surface-roughness scatterings. Using a conductance method, a fairly small value of interface trap density $({\mathrm{ D}}_{\mathrm{ it}}) = 1.56 \times 10^{12}$ cm $^{-2}$ eV $^{-1}$ was obtained for the devices with S-passivation, which was effective in mitigating the Coulombic scattering at the interface between the high-k dielectric layer and the In0.7Ga0.3As surface-channel layer.

The electronic structure of an atomic-layer-deposited MoS2 monolayer on SiO2 was investigated using X-ray absorption spectroscopy (XAS) and synchrotron X-ray photoelectron spectroscopy (XPS). The angle-dependent evolution of the XAS spectra and the photon-energy-dependent evolution of the XPS spectra were analyzed in detail using an ab-initio electronic structure simulation. Although similar to the theoretical spectra of an ideal free-standing MoS2 ML, the experimental spectra exhibit features that are distinct from those of an ideal ML, which can be interpreted as a consequence of S-O van der Waals (vdW) interactions. The strong consensus among the experimental and theoretical spectra suggests that the vdW interactions between MoS2 and adjacent SiO2 layers can influence the electronic structure of the system, manifesting a substantial electronic interaction at the MoS2-SiO2 interface.

A two-dimensional electron gas (2DEG) was formed at the interface of an ultrathin Al2O3/TiO2 heterostructure that was fabricated using atomic layer deposition (ALD) at a low temperature (

Metal and transition-metal dichalcogenide (TMD) hybrid systems have been attracting growing research attention because exciton-plasmon coupling is a desirable means of tuning the physical properties of TMD materials. Competing effects of metal nanostructures, such as the local electromagnetic field enhancement and luminescence quenching, affect the photoluminescence (PL) characteristics of metal/TMD nanostructures. In this study, we prepared TMD MoS2 monolayers on hexagonal arrays of Au nanodots and investigated their physical properties by micro-PL and surface photovoltage (SPV) measurements. MoS2 monolayers on bare Au nanodots exhibited higher PL intensities than those of MoS2 monolayers on 5-nm-thick Al2O3-coated Au nanodots. The Al2O3 spacer layer blocked charge transfer at the Au/MoS2 interface but allowed the transfer of mechanical strain to the MoS2 monolayers on the nanodots. The SPV mapping results revealed not only the electron-transfer behavior at the Au/MoS2 contacts but also the lateral drift of charge carriers at the MoS2 surface under light illumination, which corresponds to nonradiative relaxation processes of the photogenerated excitons.

We investigated the effects of quantum confinement in determining the interface traps (Dit) and border traps (Nbt) of ALD deposited Al2O3 with temperature variations onto InxGa1-xAs on a 300-mm Si (001) substrate. We also analysed the impact of these effects on the total gate capacitance of high-k/Si and high-k/InxGa1-xAs structures using 1D Poisson-Schrodinger solver simulation tool (Nextnano). While quantum confinement has no or very little impact on the gate capacitance of high-k/Si structure, it has a considerably high amount of impact on the high-k/InxGa1-xAs structures and substantially lowers the total gate capacitance. To reflect the actual thickness between the insulator-semiconductor interface and charge centroid, capacitance-equivalent-thickness was used to reflect the effects of quantum confinement in the InxGa1-xAs layer. The Dit and Nbt values extracted using capacitance-equivalent-thickness were observed to be around 10% and 25%, respectively, higher than the values of extraction with equivalent-oxide-thickness.

Cell-cell interactions regulate intracellular signaling via reciprocal contacts of cell membranes in tissue regeneration and cancer growth, indicating a critical need of membrane-derived tools in studying these processes. Hence, cell-membrane-derived nanoparticles (CMNPs) are produced using tonsil-derived mesenchymal stem cells (TMSCs) from children owing to their short doubling time. As target cell types, laryngeal cancer cells are compared to bone-marrow-derived MSCs (BMSCs) because of their cartilage damaging and chondrogenic characteristics, respectively. Treating spheroids of these cell types with CMNPs exacerbates interspheroid hypoxia with robust maintenance of the cell-cell interaction signature for 7 days. Both cell types prefer a hypoxic environment, as opposed to blood vessel formation that is absent in cartilage but is required for cancer growth. Hence, angiogenesis is inhibited by displaying the Notch-1 aptamer on CMNPs. Consequently, laryngeal cancer growth is suppressed efficiently in contrast to improved chondroprotection observed in a series of cell and animal experiments using a xenograft mouse model of laryngeal cancer. Altogether, CMNPs execute a two-edged sword function of inducing hypoxic cell-cell packing, followed by suppressing angiogenesis to promote laryngeal cancer death and chondrogenesis simultaneously. This study presents a previously unexplored therapeutic strategy for anti-cancer and chondroprotective treatment using CMNPs.

This paper analyzes 2D photonic crystal surface-emitting laser diodes with void-containing and all-semiconductor structures by comparing their simulated mode distribution, band structure, and coupling coefficients. A photonic crystal design with a square lattice and circle atoms is considered.

We examined the chemical and local structural properties of oxidized TiN/ZnS and TiN/ZnO thin films using X-ray absorption spectroscopy (XAS). The composite films were oxidized by post-deposition annealing (PDA) under various oxygen partial pressures (P(O2)). The results of the X-ray absorption near-edge structure (XANES) analyses showed that the S and N vaporized, and a zinc titanate (ZnTiO3)-like phase formed when annealed under the oxygen ambiance. An ab initio XANES simulation as well as the extended X-ray absorption fine structure (EXAFS) analysis further resolved the local structures of ZnTiO3-like phase into high symmetry structures such as ilmenite-like or perovskite-like local structure; for instance, the local structure of TiN/ZnS films annealed with P(O2) = 2 Torr could be described as a mixture of 50% ilmenite ZnTiO3 + 30% perovskite ZnTiO3 + 20% wurtzite ZnO local structures. The formation of ZnTiO3-like local structure is also subject to the temperature during the PDA or the choice of bottom layers (ZnS or ZnO). The temperature of the TiN/ZnS-to-ZnTiO3 local structural phase transformation, was estimated to be 500–600 °C at P(O2) = 2 Torr, and ZnO as bottom layer apparently expedited such local structural evolution by supplying oxygen to TiN.

The high volumetric energy density of rechargeable Mg batteries (RMBs) gives them a competitive advantage over current Li ion batteries, which originates from the high volumetric capacity (∼3833 mA h cm

The fabrication of ultra-high-resolution micro-displays with low power consumption is essential for applications in virtual reality and augmented reality systems. In this regard, GaN-based light-emitting diodes (LEDs) have been regarded as a promising candidate for self-emissive micro-displays. However, micro-LEDs suffer from sidewall defects and low quantum efficiency at a low current. Thus, we investigated the electrical and optical properties of InGaN-based green (520 nm) LEDs as functions of V pits and chip size. With decreasing chip size, the forward voltage of all samples increased at the same injection current. The samples with V pits exhibited markedly higher current density than those without V pits. With decreasing chip size, the current densities of all the samples increased, whereas the output power at the same current density decreased. As the chip size decreased, the peak external quantum efficiency of all the samples decreased, which was attained at high current densities. Furthermore, the samples with V pits displayed more efficient current spreading behavior, smaller ideality factors, and a smaller S parameter than the ones without V pits. The emission wavelength of the small samples (

We demonstrated uniform LC alignment on IB-irradiated aluminium tin oxide (AlSnO) by controlling the annealing temperature. Physico-chemical analyses were carried out to determine the surfa...

SiO2 is one of the most important dielectric materials that is widely used in the microelectronics industry, but its growth or deposition requires high thermal budgets. Herein, we report a low-temp...

AlGaN/GaN FinMISHFETs with m-plane sidewall surface channel and various fin widths ( $\text{W}_{\textsf {fin}}$ ) were fabricated and characterized. The investigated devices have much higher current drivability due to the uniform and smooth surface of m-plane than those with the a-plane sidewall surface channel. The AlGaN/GaN FinMISHFETs with $\text{W}_{\textsf {fin}}$ smaller than 36 nm exhibit normally-off operation, high Ion/Ioff ratio of 108, and remarkable subthreshold swing (SS) smaller than 40 mV/decade in the wide current range of at least three orders. Combined with a positive threshold voltage, SS values smaller than 60 mV/decade in a wide current rage of at least three orders are among the world’s best subthreshold characteristics. Furthermore, when $\text{W}_{\textsf {fin}}$ is 31 nm, the off-state drain current is as low as 10–12 A. We show that this sharp switch is due to the simultaneous turn-on of the 2-D electron gas and the m-plane sidewall surface channel. The simulation results are carried out to show the gate-induced variation of the electron concentration within the fin structure, and the assumption of considering gate width as a function of gate bias is also developed to explain the reason for deep sub-60mV/decade in the demonstrated devices.

In this paper, we modeled the scattering-limited effective mobility (μeff) of an In0.7Ga0.3As quantum-well (QW) metal-oxidesemiconductor field-effect-transistor (MOSFET). We fabricated In0.7Ga0.3As/In0.52Al0.48As QW MOSFETs with Al2O3 = 2 nm by ALD, and the devices exhibited a μeff value close to 7000 cm2/V s at 300 K and good electrostatic integrity. Detailed analysis on μeff of the In0.7Ga0.3As/In0.52Al0.48As QW MOSFETs was performed to investigate various sources of the scattering mechanism, such as surface-roughness scattering (SRS), phonon scattering (PHS) and Coulombic scattering (CS). In doing so, we attempted to separately model the three different scattering mechanisms from their dependency upon the vertical electric field intensity (Eeff). We demonstrated that μeff of the InGaAs QW MOSFET was governed by a combination of three scattering components according to Mathiessen’s rule, yielding excellent agreement with experimental data.

To make up for the shortcomings of the suture-based approach and current coupler devices including long suturing time, exhaustive training, additional mechanical setting, and narrow working windows for size and type of diverse vessel types, a new, suture-free microneedle coupler was developed in this study. The needle shape for improved anastomosis performance and the condition for antithrombotic surface immobilization were determined. In particular, the polymer materials help to maintain healthy phenotypes of main vascular cell types. The performance in rabbit and porcine models of end-to-end vascular anastomosis indicate that this device can serve as a potent alternative to the current approaches.

We present L g = 19 nm In 0.8 Ga 0.2 As composite-channel high-electron mobility transistors (HEMTs) with outstanding DC and high-frequency characteristics. We adopted a composite-channel design with an In 0.8 Ga 0.2 As core layer that led to superior carrier transport properties. The device with L g = 19 nm displayed an excellent combination of R ON = 271 Ω-μm, g m_max = 2.5 mS/μm and f T /f max = 738/492 GHz. To understand the physical origin of such an excellent combination of DC and RF responses, we analyzed the effective mobility (μ n_eff ) and delay time for both long- and short-L g devices, revealing a very high μ n_eff value of 13,200 cm2/V•s and an average velocity under the gate (v avg ) of 6.2 × 107 cm/s. We also studied the impact of the gate-to-source spacing (L GS ) and the electrostatic integrity of the device, finding that a reduction of L GS less than 0.6 μm was of little use in improving g m_max and f T . Additionally, the intrinsic output conductance (g o_int ) had an important impact on f T in short-L g HEMTs.

The instability of transistor characteristics caused by charge trapping under positive bias temperature (PBT) stress in In0.7Ga0.3As metal oxide semiconductor field-effect transistors (MOSFETs) with single-layer Al2O3 and bi-layer Al2O3/HfO2 gate stacks was investigated. The equivalent field across the multi-gate stacks was compared with a single layer used to compare the instability of electrical characteristics. The observed threshold voltage degradation (&Delta, VT) was consistent with the phenomenon of fast transient trapping of injected electrons at pre-existing shallow defects in the high-&kappa, dielectric of HfO2, in which this charging was recovered by applying a relaxation voltage. Excluding the fast-transient charging components, the power law exponent (n), with respect to the time-dependent threshold voltage degradation, ranged from 0.3 to 0.35 for both single-layer Al2O3 and bi-layer Al2O3/HfO2 gate stacks. This long-term (slow) VT shift, which was strongly correlated with transconductance (Gm) degradation, was attributed to significant charge trapping in the border trap or/and defect sites within the high-&kappa, dielectric.

GaN-based materials are expected to show excellent immunity against short-channel effects because they have relatively lower permittivity and higher electron effective mass, compared to other materials such as Si, Ge, and In(Ga)As. To further reduce the short-channel effects, it is important to enhance the gate controllability of the device by utilizing a gate-all-around (GAA) structure. In this article, GaN vertical GAA nanowire MOSFETs with various diameters of 120, 75, and 45 nm have been fabricated. The device with a diameter of 120 nm shows a threshold voltage of 0.7 V, drain saturation voltage of 0.5 V, and subthreshold swing of 70 mV/decade, which would be suitable for low-voltage/power applications. However, the devices with smaller diameters of 75 and 45 nm show peculiar characteristics, such as a second rise of the drain current in output characteristics and a negative transconductance.

Photonic crystal surface emitting lasers (PCSELs) are a new class of laser diode, offering control over emission (wavelength, polarisation, beam shape) through photonic crystal design, as well as power scalability and low beam divergence. We present developments in 2D arrays of large scale (~150x150um) PCSELs, coherently coupled by 1mm long, 100 μm wide waveguides that can be electrically driven into loss or gain. By studying the spectral and current-power characteristics, we show coherent power scaling between multiple devices. We discuss injection locking between devices achieved through controllable 2D in-plane feedback and its effect on the near and far field emissions.

This study considers the possibility of utilizing agri-byproducts as energy sources via pelletization and torrefaction. Pellets were placed in a capsule and torrefied in an electrical furnace. Subsequently, they were cooled for 30 min, and their mass loss was measured. To investigate the resulting changes in fuel characteristics, ultimate and proximate analyses were performed, and calorific values were measured. To estimate the water absorption of the pellets, hygroscopicity evaluations were conducted. Based on the experimental results, the energy yield, lower heating value, and exergy were calculated to determine the optimum conditions for torrefaction. The calculation was performed by utilizing the useful exergy and standards applied to biomass power plants. We determined that torrefaction for agro-pellets should be conducted under low-to-intermediate temperatures (210−250 °C) within a period of 50 min. Under these conditions, 7−55% mass reductions were observed, the higher heating value increased from 4110 to 6880 kcal kg−1, and the lower heating value changed from 3780 to 6520 kcal kg−1 owing to reduced hygroscopicity. So, Agro-byproducts can contribute to the practical application by improving the heating value through torrefaction as an alternative to wood pellets.

Purpose Scanning proton therapy has dosimetric advantage over passive treatment, but has a large penumbra in low-energy region. This study investigates the penumbra reduction when multi-leaf collimators (MLCs) are used for line scanning proton beams and secondary neutron production from MLCs. Methods Scanning beam plans with and without MLC shaping were devised. Line scanning proton plan of 36 energy layers between 71.2 and 155.2 MeV was generated. The MLCs were shaped according to the cross-sectional target shape for each energy layer. The two-dimensional doses were measured through an ion-chamber array, depending on the presence of MLC field, and Monte Carlo (MC) simulations were performed. The plan, measurement, and MC data, with and without MLC, were compared at each depth. The secondary neutron dose was simulated with MC. Ambient neutron dose equivalents were computed for the line scanning with 10 × 10 × 5 cm3 volume and maximum proton energy of 150 MeV, with and without MLCs, at lateral distances of 25–200 cm from the isocenter. The neutron dose for a wobbling plan with 10 × 10 × 5 cm3 volume was also evaluated. Results The lateral penumbra width using MLC was reduced by 23.2% on average, up to a maximum of 32.2%, over the four depths evaluated. The ambient neutron dose equivalent was 18.52% of that of the wobbling beam but was 353.1% larger than the scanning open field. Conclusions MLC field shaping with line scanning reduced the lateral penumbra and should be effective in sparing normal tissue. However, it is important to investigate the increase in neutron dose.

When wood pellets with high moisture content are used as fuel, the generation of tar during the combustion process increases. As a result, various problems occur, including decrease in thermal efficiency, increase in emission of polluting gases, and the need to clean the combustion chamber. To address this problem, this research applied refractory insulation where a fluid dynamics simulation indicated that thermal stresses most severely occurred, and cleaning was most often required. The fire-tube and baffle were then modified to compensate for the decrease in efficiency. A modified boiler was manufactured based on the simulation, and the experiment was performed. Under the no-tar condition, the thermal efficiencies of the control and modified boilers were found to be 92.20% and 90.63%, but once tar had accreted onto the combustion chamber walls, the modified boiler is more efficient at 82.55% compared to 81.79% for the control boiler. The changes in thermal efficiency due to the presence of tar were predicted using computational fluid dynamics simulations of no-tar and tar-accreted conditions, showing 91.83% and 85.25%, respectively, in the control and 92.05% and 87.18%, respectively, in the modified boiler, providing good agreement with the experimental results.

We report the field-effect transistors using quasi-two-dimensional electron gas generated at an ultrathin (∼10 nm) Al2O3/TiO2 heterostructure interface grown via atomic layer deposition (ALD) on a SiO2/Si substrate without using a single crystal substrate. The 2DEG at the Al2O3/TiO2 interface originates from oxygen vacancies generated at the surface of the TiO2 bottom layer during ALD of the Al2O3 overlayer. High-density electrons (∼1014 cm–2) are confined within a ∼2.2 nm distance from the Al2O3/TiO2 interface, resulting in a high on-current of ∼12 μA/μm. The ultrathin TiO2 bottom layer is easy to fully deplete, allowing an extremely low off-current, a high on/off current ratio over 108, and a low subthreshold swing of ∼100 mV/decade. Via the implementation of ALD, a mature thin-film process can facilitate mass production as well as three-dimensional integration of the devices.

We have fabricated and characterized Lg = 0.5 μm In0.52Al0.48As/In0.7Ga0.3As pseudomorphic high-electron-mobility-transistors (PHEMTs) on a 3-inch InP substrate. Stepper-based photo-lithography was used in all the process steps for device fabrication, aiming to miniaturize key device geometries, such as gate-to-source and gate-to-drain spacing. The fabricated device with Lg = 0.5 μm exhibits an excellent maximum transconductance (gm_max) of 1.9 S/mm at VDS = 1.5 V and an ON-resistance (RON) of below 0.4 Ω-mm. A high value of gm in our device leads to a fantastic combination of current-gain cut-off frequency (fT) of 120 GHz and maximum oscillation frequency (fmax) of 366 GHz at VDS = 0.8 V. These remarkable characteristics stem from the compact geometry design of the In0.52Al0.48As/In0.7Ga0.3As PHEMTs with LGS = LGD = 0.4 μm, coupled with an optimized gate recess process that yields tight control of side-recess spacing (Lside). More importantly, the product of fT and Lg in this work yields 60 GHz-μm which is the highest in any field-effect-transistor (FET) technology on any material system.

GaN gate-all-around (GAA) vertical nanowire MOSFET (VNWMOSFET) with channel length of 300 nm and diameter of 120 nm, the narrowest GaN-based vertical nanowire transistor ever achieved from the top-down approach, was fabricated by utilizing anisotropic side-wall wet etching in TMAH solution and photoresist etch-back process. The VNWMOSFET exhibited output characteristics with very low saturation drain voltage of less than 0.5 V, which is hardly observed from the wide bandgap-based devices. Simulation results indicated that the narrow diameter of the VNWMOSFET with relatively short channel length is responsible for the low voltage operation. The VNWMOSFET also demonstrated normally-off mode with threshold voltage (VTH) of 0.7 V, extremely low leakage current of ∼10−14 A, low drain-induced barrier lowering (DIBL) of 125 mV/V, and subthreshold swing (SS) of 66–122 mV/decade. The GaN GAA VNWMOSFET with narrow channel diameter investigated in this work would be promising for new low voltage logic application.

We have investigated the effect of chip size on the forward voltage, light output, emission image and spectral shift of InGaN based green LEDs (518 nm) as a function of current density. The size of the chips was varied from 10 to 100 µm. The smaller chips exhibited higher light output power although the lower output powers were obtained at the higher current densities. Furthermore, the smallest devices showed the better current spreading at higher current densities. It was shown that green micro-LEDs (µLEDs) experienced spectral shift when drive current and chip size increased, but the shift was more significantly dependent on dc drive current compared with chip size. The relation between the electroluminescence characteristics and current density of different-size devices revealed that the devices more dominantly went through blue shift than red shift. However, at the same current density, the peak of the devices was not shifted when the device size changed. Dependence of the chip size and current density on the spectral shift of green µLEDs will be described and discussed in terms of effects of band-filling and stress relaxation.

In this study, to improve the fuel characteristics of unused agro-byproducts and utilize these as an energy source after pelletizing, a thermochemical process termed as surface torrefaction was developed. After torrefaction, the amount of available energy and energy yield decreased due to mass reduction. Thus, surface torrefaction minimized the amount of input energy and energy yield. During this process, the carbonized surface of pellets and any moisture was removed from inside the pellet which is advantageous for storage and transportation. Changes in color and physiochemical characteristics were also observed. The calorific value and moisture content of the wood pellet (WP) and pepper stem pellet (PP) before surface torrefaction were 20.1 MJ kg−1 and 8% and 18.1 MJ kg−1 and 6.5%, respectively. After surface torrefaction, the WP and PP calorific values and energy yields were: 20.3–20.7 MJ kg−1 and 87.3–92.5%, and 18.5–20.1 MJ kg−1 and 86.8–95.9%, respectively. After torrefaction and surface torrefaction, the change in mass yield and fuel characteristics were compared. The optimal conditions for WP and PP treatments, considering hygroscopicity, calorific value, and energy yield, were determined as 300 °C for 4.5 min and 300 °C for 5 min, respectively at surface torrefaction.

We investigated the electrical performance of near ultraviolet (NUV) (390 nm) light-emitting diodes (LEDs) fabricated with various semi-transparent Cr/ITO n-type contacts. It was shown that after annealing at 400 °C, Cr/ITO (10 nm/40 nm) contact was ohmic with a specific contact resistance of 9.8 × 10−4 Ωcm2. NUV AlGaN-based LEDs fabricated with different Cr/ITO (6–12 nm/40 nm) electrodes exhibited forward-bias voltages of 3.27–3.30 V at an injection current of 20 mA, which are similar to that of reference LED with Cr/Ni/Au (20 nm/25 nm/200 nm) electrode (3.29 V). The LEDs with the Cr/ITO electrodes gave series resistances of 10.69–11.98 Ω, while the series resistance is 10.84 Ohm for the reference LED. The transmittance of the Cr/ITO samples significantly improved when annealed at 400 °C. The transmittance (25.8–45.2% at 390 nm) of the annealed samples decreased with increasing Cr layer thickness. The LEDs with the Cr/ITO electrodes exhibited higher light output power than reference LED (with Cr/Ni/Au electrode). In particular, the LED with the Cr/ITO (12 nm/40 nm) electrode showed 9.3% higher light output power at 100 mA than reference LED. Based on the X-ray photoemission spectroscopy (XPS) and electrical results, the ohmic formation mechanism is described and discussed.

In this letter, we have investigated the properties of In0.53Ga0.47As quantum-well (QW) metal–oxide–semiconductor field-effect-transistors (MOSFETs) on a 300-mm(100) Si wafer. We have explored the impact of scaling down In0.53Ga0.47As channel thickness ( $\text{t}_{\mathrm {ch}})$ from 15 to 5 nm. The fabricated devices show excellent electrostatic integrity, such as subthreshold-swing (SS) $\mu _{\textit {n$\_{}$eff}})$ of the fabricated devices to investigate the carrier transport properties of the InGaAs MOSFETs with different values of $\text{t}_{\mathrm {ch}}$ . The device with $\text{t}_{\mathrm {ch}} = 15$ nm displayed a value of $\mu _{\textit {n$\_{}$eff}} = 2,190$ cm2/V-s at room temperature. This valuewas found to decrease as $\text{t}_{\mathrm {ch}}$ was scaled down.

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.