Electron work function (EWF) has demonstrated its great promise in materials analysis and design, particularly for single-phase materials, e.g., solute selection for optimal solid-solution strengthening.
View Article and Find Full Text PDFGroup-III monochalcogenides of two-dimensional (2D) layered materials have attracted widespread attention among scientists due to their unique electronic performance and interesting chemical and physical properties. Indium sulfide (InS) is attracting increasing interest from scientists because it has two distinct crystal structures. However, studies on the synthesis of highly crystalline, large-area, and atomically thin-film InS have not been reported thus far.
View Article and Find Full Text PDFConvergent beam electron diffraction (CBED) in transmission electron microscopy (TEM) was applied to determine local carbon concentrations in low-carbon transformation-induced plasticity (TRIP) steels. High-order Laue-zone (HOLZ) lines were experimentally obtained for comparison with simulation results. A new procedure for calculating carbon content is thus proposed.
View Article and Find Full Text PDFNegative voltage modulated multi-level resistive switching with quantum conductance during staircase-type RESET and its transport characteristics in Cr/BaTiO/TiN structure have been investigated for the first time. The as-deposited amorphous BaTiO film has been confirmed by high-resolution transmission electron microscopy. X-ray photo-electron spectroscopy shows different oxidation states of Ba in the switching material, which is responsible for tunable more than 10 resistance states by varying negative stop voltage owing to slow decay value of RESET slope (217.
View Article and Find Full Text PDFA 15-nm-thick GdO x membrane in an electrolyte-insulator-semiconductor (EIS) structure shows a higher pH sensitivity of 54.2 mV/pH and enzyme-free hydrogen peroxide (H2O2) detection than those of the bare SiO2 and 3-nm-thick GdO x membranes for the first time. Polycrystalline grain and higher Gd content of the thicker GdO x films are confirmed by transmission electron microscopy (TEM) and X-ray photo-electron spectroscopy (XPS), respectively.
View Article and Find Full Text PDFHigh threading dislocation (TD) density in GaN-based devices is a long unresolved problem because of the large lattice mismatch between GaN and the substrate, which causes a major obstacle for the further improvement of next-generation high-efficiency solid-state lighting and high-power electronics. Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire substrate, on which a near strain-free GaN compliant buffer layer was grown by remote plasma atomic layer deposition. This "compliant" buffer layer is capable of relaxing strain due to the absorption of misfit dislocations in a region within ~10 nm from the interface, leading to a high-quality overlying GaN epilayer with an unusual TD density as low as 2.
View Article and Find Full Text PDFConductive and transparent multilayer thin films consisting of three alternating layers (TiO2/Ag/SiO2, TAS) have been fabricated for applications as transparent conducting oxides. Metal oxide and metal layers were prepared by electron-beam evaporation with ion-assisted deposition, and the optical and electrical properties of the resulting films as well as their energy bounding characteristics and microstructures were carefully investigated. The optical properties of the obtained TAS material were compared with those of well-known transparent metal oxide glasses such as ZnO/Ag/ZnO, TiO2/Ag/TiO2, ZnO/Cu/ZnO, and ZnO/Al/ZnO.
View Article and Find Full Text PDFEnhanced resistive switching phenomena of IrOx/GdOx/W cross-point memory devices have been observed as compared to the via-hole devices. The as-deposited Gd2O3 films with a thickness of approximately 15 nm show polycrystalline that is observed using high-resolution transmission electron microscope. Via-hole memory device shows bipolar resistive switching phenomena with a large formation voltage of -6.
View Article and Find Full Text PDFTransparent conducting ZnO/Ag/ZnO multilayer electrodes having electrical resistance much lower than that of widely used transparent electrodes were prepared by ion-beam-assisted deposition (IAD) under oxygen atmosphere. The optical parameters were optimized by admittance loci analysis to show that the transparent conducting oxide (TCO) film can achieve an average transmittance of 93%. The optimum thickness for high optical transmittance and good electrical conductivity was found to be 11 nm for Ag thin films and 40 nm for ZnO films, based on the admittance diagram.
View Article and Find Full Text PDFImproved resistive switching memory characteristics by controlling the formation polarity in an IrOx/Al2O3/IrOx-ND/Al2O3/WOx/W structure have been investigated. High density of 1 × 1013/cm2 and small size of 1.3 nm in diameter of the IrOx nano-dots (NDs) have been observed by high-resolution transmission electron microscopy.
View Article and Find Full Text PDFIn this study, we investigated the interplay of three-dimensional morphologies and the photocarrier dynamics of polymer/inorganic nanocrystal hybrid photoactive layers consisting of TiO(2) nanoparticles and nanorods. Electron tomography based on scanning transmission electron microscopy using high-angle annular dark-field imaging was performed to analyze the morphological organization of TiO(2) nanocrystals in poly(3-hexylthiophene) (P3HT) in optimal solar cell devices. The Three-dimensional (3D) morphologies of these hybrid films were correlated with the photocarrier dynamics of charge separation, transport, and recombination, which were comprehensively probed by various transient techniques.
View Article and Find Full Text PDFSi nanocrystals embedded in a SiO2 matrix and an n-type Al-doped ZnO (ZnO:Al) layer were applied to improve the external quantum efficiency from Si in n- ZnO/SiO2-Si nanocrystals-SiO2/p-Si heterojunction light-emitting diodes (LEDs). The Si nanocrystals were grown by low pressure chemical vapor deposition and the ZnO:Al layer was prepared by atomic layer deposition. The n-type ZnO:Al layer acts as an electron injection layer, a transparent conductive window, and an anti-reflection coating to increase the light extraction efficiency.
View Article and Find Full Text PDFThis study demonstrates amplified spontaneous emission (ASE) of the ultraviolet (UV) electroluminescence (EL) from ZnO at lambda~380 nm in the n-ZnO/ZnO nanodots-SiO(2) composite/p- Al(0.12)Ga(0.88)N heterojunction light-emitting diode.
View Article and Find Full Text PDF