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Production of fresh water based on a renewable energy source is one of the most important global challenges for mankind due to ever-accelerating climate changes. Solar thermal evaporation shows promise for overcoming the water scarcity problem by utilizing solar energy, the most abundant and clean energy source. To enhance the performance of solar evaporators, interfacial solar evaporators have been introduced, which harness solar energy onto the water surface. To enable energy conversion and water evaporation at the interfaces of a solar evaporator, multi-scale heat and water transport have been investigated. Furthermore, various light-absorbing materials and system configurations have been studied to achieve the theoretical maximum performance. The fundamental physics of the interfacial solar evaporator, including thermal and water transport, and a broad range of interfacial solar evaporator devices in terms of the fabrication techniques and its structures are reviewed.

Organic–inorganic hybrid halide perovskite solar cells are promising for next-generation thin-film solar cells, demonstrating power conversion efficiency exceeding 25%. In particular, single-crystal perovskite materials are estimated to possess superior optoelectronic properties that can further enhance the efficiency. However, fabricating thin single-crystal perovskite for a light-absorber layer remains challenging. In this study, a 40-µm-thick single-crystalline MAPbBr3 perovskite is fabricated by inverse temperature crystallization (ITC) with a selective seed-transfer technique. By using a separate seed growth process and a seed-transfer process, a 16.23-mm2-large single domain high-quality single-crystalline MAPbBr3 perovskite can be grown without additional nucleation. The grown single-crystal MAPbBr3 exhibits a low surface roughness of 0.51 nm and low trap density of 7.61 × 108 cm−3. We also fabricate solar cells with single-crystalline MAPbBr3 using a glass substrate coated with SnO2 and indium-tin-oxide thin films. The single-crystal MAPbBr3-based solar cells demonstrate a power conversion efficiency of 4.31%.

Solar cells that are semitransparent and highly efficient can find diverse applications in automobile windows, building walls, and wearable devices. Here, we present a semitransparent perovskite thin-film solar cell with an Ag nanogrid transparent electrode, where electrospun poly(ethylene oxide) (PEO) nanofibers are used as an etching mask. Directional electrospinning has allowed us to obtain a grid-shaped electrode of well-aligned Ag nanogrids. The performance of transparent electrodes can be controlled by the electrospinning conditions and the choice of substrate materials. We theoretically analyze the transmittance and sheet resistance of the electrode. Furthermore, transferable Ag nanogrid transparent electrodes are fabricated on poly(dimethylsiloxane) (PDMS) substrates for application in semitransparent perovskite solar cells. Using an electrode that shows a high transmittance (92.7%) with a low sheet resistance (18.0 Ω·sq-1), a semitransparent perovskite thin-film solar cell demonstrates average visible wavelength transmittance, power conversion efficiency, and light utilization efficiency rates as high as 25.2, 12.7, and 3.21%, respectively.

Solar thermal distillation is a promising way to harvest clean water due to its sustainability. However, the energy density of solar irradiation inevitably demands scalability of the systems. To realize practical applications, it is highly desirable to fabricate meter-scale solar evaporator panels with high capillary performance as well as optical absorptance using scalable and high-throughput fabrication methods. Here, we demonstrate a truly scalable fabrication process for a bi-facial solar evaporator with copper oxide dendrites via the hydrogen bubble templated electrochemical deposition technique. Furthermore, we construct a theoretical model combining capillarity and evaporative mass transfer, which leads to optimal operation conditions and wick characteristics, including superhydrophilicity, extreme capillary performance, and omni-angular high optical absorptance. The fabricated porous surfaces with excellent capillary performance and productivity provide a pathway toward a highly efficient bi-facial solar evaporator panel with meter-level scalability.

The influence of anion composition on the electrical characteristics of amorphous zinc-oxynitride thin-film transitors (TFTs) is investigated and quantitatively modeled, with emphasis on the subgap density of states (DOS). As the ratio of N to (N + O) increases, the density of valence band tail states increases, followed by narrowing of the bandgap and a decrease in the density of conduction band tail states, which in turn is followed by either a higher field-effect mobility or a better subthreshold swing; each of these effects is explained. Furthermore, the anion composition dependence of the transconductance degradation at a high bias is analyzed on the basis of the proposed model. In addition, the effects of the N/(N + O) ratio on carrier density and field-effect mobility are quantitatively explained by the ionized nitrogen vacancy ( ${V}_{\text {N}}^{{1.3}+}$ ) model observed in shallow donor peak in the DOS and by the charge-controlled mobility model, respectively. Finally, the effect of nanocrystalline structure mixed with amorphous on transport properties is discussed.

We present an equivalent circuit model with improved accuracy for 1.5-μm germanium waveguide-type vertical photodetectors on a silicon-on-insulator substrate. Our model consists of passive circuit components, two current sources for photogenerated carrier transports, and one noise current source. Model parameters are extracted from electrical S-parameter measurements, TCAD simulations of photodetection frequency responses, and noise measurements. The resulting equivalent circuit model accurately provides photodetection frequency responses at different bias voltages and should be of great use for high-performance optical receiver circuit design.

8 band k → · p → method is used to calculate subband structures of InGaAs inversion layers accounting for strong coupling between conduction and valence bands around Γ point as well as quantum confinement. Inversion layer mobility is computed employing Kubo–Greenwood formalism. Scatterings due to acoustic phonons, polar optical phonons, ionized impurities, interface fixed charges, surface roughness, and alloy disorder are included. The simulated low-field electron mobility results are in good agreement with experimental data with and without an InP capping layer.

We report on the selective area growth (SAG) of high quality InP layers on patterned (0 0 1)Si substrates at various growth temperatures by metal organic chemical vapor deposition. Thin InP and GaP layers were used as intermediate buffer layers between patterned Si surface and high temperature (HT) InP layer. The growth temperatures of HT InP layers on patterned substrate had strong effect on their growth behaviors including surface morphology. The SAG InP layers grown at 650 °C and 550 °C exhibited the typical {1 1 1} facets and the smooth (0 0 1) top surface, respectively. Anti-phase domain boundaries and defects were trapped by lateral sidewalls of the etched Si substrate. Through the defect necking effect within the etched Si surface, defect-free InP layers with atomically smooth surface were obtained at a growth temperature of 550 °C.

We present a 25-Gb/s optical transmitter composed of a Si ring modulator and CMOS driver circuit. The Si ring modulator is realized with 220-nm Si-on-insulator process and the driver circuit with 65-nm CMOS process. The modulator and the driver are hybrid-integrated on the printed circuit board with bonding wires. The driver is designed so that the parasitic bonding wire inductance provides enhanced driver bandwidth. The transmitter successfully demonstrates 25-Gb/s operation.

Atomic-layer-deposited Al 2 O 3 films were grown on ultrathin-body In 0.53 Ga 0.47 As substrates for III-V compound-semiconductor-based devices. Interface sulfur (S) passivation was performed with wet processing using ammonium sulfide ((NH 4 ) 2 S) solution, and dry processing using post-deposition annealing (PDA) under a H 2 S atmosphere. The PDA under the H 2 S atmosphere resulted in a lower S concentration at the interface and a thicker interfacial layer than the case with (NH 4 ) 2 S wet-treatment. The electrical properties of the device, including the interface property estimated through frequency dispersion in capacitance, were better for (NH 4 ) 2 S wet-treatment than the PDA under a H 2 S atmosphere. They might be improved, however, by optimizing the process conditions of PDA. The PDA under a H 2 S atmosphere following (NH 4 ) 2 S wet-treatment resulted in an increased S concentration at the interface, which improved the electrical properties of the devices.

The effect of additional HCl flow on the growth of a-plane GaN layers on r-plane sapphire by hydride vapor-phase epitaxy was investigated. Upon increasing the additional HCl flow rate, the surface roughness of the a-plane GaN layers, as measured by atomic force microscopy, reduced. The crystal quality of a-plane GaN, however, deteriorated, as confirmed by high stacking fault density observed by transmission electron microscopy, relating to the increased nuclei density and mosaicity and a high full width at half maximum in the ω-scan X-ray rocking curve. These observations were attributed to the large difference of growth rate and etch rate along c-direction, and m-direction of a-plane GaN, which were originated from the surface energetics of the crystallographic planes of GaN.

The fabrication of thin-film transistor devices incorporating active semiconductors based on zinc oxynitride (ZnON) compound is presented. It is demonstrated that the addition of appropriate dopant, gallium, in ZnON, suppresses the formation of shallow donor, nitrogen vacancies, and significantly improves electrical characteristics of the resulting TFT. The Ga:ZnON devices with field-effect mobility values exceeding 50 cm2/Vs are achieved, which makes them suitable as switching or driving elements in next-generation flat-panel displays.

We present a model for charged dislocations effects on III-V compound semiconductor based FinFETs performance. The model is developed to obtain momentum relaxation time and, from it, key device performance parameters such as effective mobility, threshold voltage, and finally saturation drain current. We find out that charged threading edge dislocation density of a FinFET channel should be smaller than about 107cm-2to ignore the dislocation scattering impact on the device performance which is roughly one order more strict condition than previously known condition for wurtzite GaN.

Fly ash has been used in the construction of nuclear power plant faced with marine environment. The influence of supplementary fly ash on the mechanical properties of high performance concrete (HPC) has been investigated in this study. Selected test variables were fly ash replacement ratio with four levels (0 %, 10%, 20% and 30%) and curing days (28 days, 56 days and 91 days). This paper outlines an experimental study on compressive strength, splitting tensile strength, modulus of elasticity and Poissons ratio of HPC using ordinary Portland cement and fly ash.

We demonstrate the technique of determining Si micro-ring modulator device parameters for achieving optimal modulation performance. Our technique is based on a simple analytic equation and confirmed by measurement and numerical solutions. Using this technique, we determine the optimal ring radius for different data rates.

A cation-exchange nanofiber poly(vinylidene fluoride) (PVdF) membrane was prepared by a radiation-induced graft polymerization (RIGP) of sodium styrene sulfonate (NaSS) in the presence of the polymerizable access agents in methanol solution. The used polymerizable access agents include styrene, acrylic acid, and vinyl pyrrolidone. The anion-exchange nanofiber PVdF membrane was also prepared by RIGP of glycidyl methacrylate (GMA) and its subsequent chemical modification. The successful preparations of cation- and anion-exchange PVdF membranes were confirmed via SEM, XPS and thermal analysis. The content of the grafting yield, ion-exchange group, and water uptake was in the range of 30.0~32.3%, 2.81~3.01 mmol/g and 66.6~147%, respectively. The proton conductivity at 20 was in the range of 0.020~0.053 S/cm. From the result, the prepared ionexchange PVdF membrane can be used as a separator in battery cells.

We report on new fabrication methods for a transparent, hierarchical, and patterned electrode comprised of either carbon nanotubes or zinc oxide nanorods. Vertically aligned carbon nanotubes or zinc oxide nanorod arrays were fabricated by either chemical vapor deposition or hydrothermal growth, in combination with photolithography. A transparent conductive graphene layer or zinc oxide seed layer was employed as the transparent electrode. On the patterned surface defined using photoresist, the vertically grown carbon nanotubes or zinc oxides could produce a concentrated electric field under applied DC voltage. This periodic electric field was used to align liquid crystal molecules in localized areas within the optical cell, effectively modulating the refractive index. Depending on the material and morphology of these patterned electrodes, the diffraction efficiency presented different behavior. From this study, we established the relationship between the hierarchical structure of the different electrodes and their efficiency for modulating the refractive index. We believe that this study will pave a new path for future optoelectronic applications.

The chemical resistance of textile geogrids to alkaline conditions was studied. From the results, textile geogrids manufactured from PET yarn show strong resistance in the case of light alkaline condition (pH 9) at room temperature. However, under severe alkaline conditions at high temperature the raw mechanical properties could not be maintained. From the results, strength retention after chemical degradation was calculated and used to determine the reduction factor for application in revetment reinforcement design.

A new cooling duct system was developed in order to increase the refrigerator performance in terms of uniform temperature distribution particle image velocimetry (PIV) and the commercial software FLUENT was used to compare the performance of the conventional cooling system with the new cooling system. The new cooling system effectively cooled the door basket region, thus increasing the uniformity of the temperature distribution in the refrigeration compartment.

8 band k · p method is used to calculate subband structures of InGaAs inversion layers accounting for strong coupling between conduction and valence bands around Γ point as well as quantum confinement. Inversion layer mobility is computed employing Kubo-Greenwood formalism. Scatterings due to acoustic phonons, polar optical phonons, ionized impurities, interface fixed charges, surface roughness, and alloy disorder are included. The simulated low-field electron mobility results are in good agreement with in-house experimental data with and without an InP capping layer.

We present a new small-signal model for the modulation frequency response of a Si micro-ring modulator. The model is based on the coupled-mode theory and has the well-known second-order system characteristics. The accuracy of the model is confirmed with measured Si MRM small-signal frequency response.

High speed thin film transistors (TFTs) are in great need for next-generation TVs which will employ ultra high definition resolution (3840×2160) panels and possibly include multi-view autostereoscopic 3D technology which will negate the use of glasses for 3D viewing mode. In order to achieve high mobility devices, various types of metal oxide semiconductors have been extensively studied, including the most popular In-Ga-Zn-O, with typical field effect mobilities ranging between 10 to 30 cm2/Vs. Although these numbers are much higher than that of conventional amorphous silicon (0.5~1.0 cm2/Vs) TFTs, there is a strong demand for even higher mobility semiconductors which can exhibit excellent uniformity over a large area.

Stackable select devices such as the oxide p-n junction diode and the Schottky diode (one-way switch) have been proposed for non-volatile unipolar resistive switching devices; however, bidirectional select devices (or two-way switch) need to be developed for bipolar resistive switching devices. Here we report on a fully stackable switching device that solves several problems including current density, temperature stability, cycling endurance and cycle distribution. We demonstrate that the threshold switching device based on As-Ge-Te-Si material significantly improves cycling endurance performance by reactive nitrogen deposition and nitrogen plasma hardening. Formation of the thin Si₃N₄ glass layer by the plasma treatment retards tellurium diffusion during cycling. Scalability of threshold switching devices is measured down to 30 nm scale with extremely fast switching speed of ~2 ns.

As silicon-based electronics approach the limit of improvements to performance and capacity through dimensional scaling, attention in the semiconductor field has turned to graphene, a single layer of carbon atoms arranged in a honeycomb lattice. Its high mobility of charge carriers (electrons and holes) could lead to its use in the next generation of high-performance devices. Graphene is unlikely to replace silicon completely, however, because of the poor on/off current ratio resulting from its zero bandgap. But it could be used to improve silicon-based devices, in particular in high-speed electronics and optical modulators.

We investigate the low-frequency noise (LFN) properties of amorphous zinc oxynitride (a-ZnON) thin-film transistors (TFTs) exhibiting high field-effect mobilities ranging from 48.5 to 118.9 cm2/ $\text {V}\cdot \text {s}$ , depending on the gas flow rates during the deposition process. The measured noise power spectral density of the drain current shows that the LFN in a-ZnON TFTs obeys the classical 1/ $f$ noise theory, i.e., it is proportional to 1/ $f^{\mathrm {\gamma }}$ with $\gamma \sim 1$ in the frequency range from 10 Hz to 1 kHz. The LFN from the a-ZnON TFT is successfully interpreted by the correlated number fluctuation-mobility fluctuation model. The near-interface dielectric trap density ( $N_{T})$ and the Coulomb scattering coefficient ( $\alpha _{S})$ extracted from the measured LFN in a-ZnON TFTs are similar to those from the previously reported values for amorphous indium–gallium–zinc oxide TFTs. The relatively large values of $N_{T}$ and $\alpha _{S}$ from the a-ZnON TFTs formed under O2-rich environment are mainly attributed to the high degree of disorder of the a-ZnON channel layer caused by the energetically broad and high density of subgap tail states.

A 1.4 μm-pitch pixel of CMOS image sensor, which is the smallest to date, has been successfully developed and integrated into 8M density for the first time. To overcome the crucial degradation of the saturation charge and sensitivity, a novel photodiode structure extended under transfer gate and an elaborate optical design including very thin tungsten pixel routing with 65 nm-grade design rules are introduced, which result in enhanced electrical and optical performance.

A single sheet of graphene dramatically changes the nonlinear response of a silicon photonic crystal, enabling ultralow-power optical bistability, self-induced regenerative oscillation and coherent four-wave mixing.

We simulate resistance distributions of multilevel oxide bipolar resistive random access memories (ReRAMs) through a physical model with Monte Carlo method. The model is used to explain frequently noticed proportionality relationship between distributions of resistances and multi-levels program voltages. By comparing with the experimental results obtained with TaOx/Ta2O5 bipolar ReRAM, the model is verified to have a good consistency with experiments not only qualitatively but also quantitatively. We demonstrate that the resistance distributions responses are basically determined by the ion migration barrier in the resistance varying thin oxide layer which means that it is a nearly intrinsic material property.