Impact of Channel Thickness and Doping Concentration for Normally-Off Operation in Sn-Doped -GaO Phototransistors.

We demonstrate a Sn-doped monoclinic gallium oxide (-GaO)-based deep ultraviolet (DUV) phototransistor with high area coverage and manufacturing efficiency. The threshold voltage () switches between negative and positive depending on the -GaO channel thickness and doping concentration. Channel depletion and Ga diffusion during manufacturing significantly influence device characteristics, as validated through computer-aided design (TCAD) simulations, which agree with the experimental results.

Wide-Range Synaptic Current Responses with a Liquid Ga Electrode via a Surface Redox Reaction in a NaOH Solution at Different Molar Concentrations.

A liquid Ga-based synaptic device with two-terminal electrodes is demonstrated in NaOH solutions at 50 °C. The proposed electrochemical redox device using the liquid Ga electrode in the NaOH solution can emulate various biological synapses that require different decay constants. The device exhibits a wide range of current decay times from 60 to 320 ms at different NaOH mole concentrations from 0.

Synaptic Current Response of a Liquid Ga Electrode via a Surface Electrochemical Redox Reaction in a NaOH Solution.

An ionic device using a liquid Ga electrode in a 1 M NaOH solution is proposed to generate artificial neural spike signals. The oxidation and reduction at the liquid Ga surface were investigated for different bias voltages at 50 °C. When the positive sweep voltage from the starting voltage ( ) of 1 V was applied to the Ga electrode, the oxidation current flowed immediately and decreased exponentially with time.

Improved Light Harvesting of Fiber-Shaped Dye-Sensitized Solar Cells by Using a Bacteriophage Doping Method.

Fiber-shaped solar cells (FSCs) with flexibility, wearability, and wearability have emerged as a topic of intensive interest and development in recent years. Although the development of this material is still in its early stages, bacteriophage-metallic nanostructures, which exhibit prominent localized surface plasmon resonance (LSPR) properties, are one such material that has been utilized to further improve the power conversion efficiency (PCE) of solar cells. This study confirmed that fiber-shaped dye-sensitized solar cells (FDSSCs) enhanced by silver nanoparticles-embedded M13 bacteriophage (Ag@M13) can be developed as solar cell devices with better PCE than the solar cells without them.

Impact of Al doping on a hydrothermally synthesized β-GaO nanostructure for photocatalysis applications.

Aluminum (Al)-doped beta-phase gallium oxide (β-GaO) nanostructures with different Al concentrations (0 to 3.2 at%) are synthesized using a hydrothermal method. The single phase of the β-GaO is maintained without intermediate phases up to Al 3.

Effects of Moisture-Proof Back Passivation Layers of AlO and AlTiO Films on Efficiency Improvement and Color Modulation in Transparent a-Si:H Solar Cells.

In this study, the back passivation layers (BPLs) were developed to protect hydrogenated amorphous silicon (a-Si:H) thin films of transparent solar cells from humidity and contaminants. Metal oxide compound films with Al (AlO) and Ti (AlTiO (ATO)) were fabricated by plasma-enhanced atomic layer deposition for the BPLs on transparent solar cells. The BPLs of AlO films applied to the transparent solar cells were deposited in different thicknesses to evaluate the performance, and the ATO film thickness was fixed at 30 nm.

Fast-Response Colorimetric UVC Sensor Made of a GaO Photocatalyst with a Hole Scavenger.

A fast-response colorimetric ultraviolet-C (UVC) sensor was demonstrated using a gallium oxide (GaO) photocatalyst with small amounts of triethanolamine (TEOA) in methylene blue (MB) solutions and a conventional RGB photodetector. The color of the MB solution changed upon UVC exposure, which was observed using an in situ RGB photodetector. Thereby, the UVC exposure was numerically quantified as an MB reduction rate with the value of the photodetector, which was linearly correlated with the measured spectral absorbance using a UV-Vis spectrophotometer.

The Characteristics of Transparent Non-Volatile Memory Devices Employing Si-Rich SiO as a Charge Trapping Layer and Indium-Tin-Zinc-Oxide.

We fabricated the transparent non-volatile memory (NVM) of a bottom gate thin film transistor (TFT) for the integrated logic devices of display applications. The NVM TFT utilized indium-tin-zinc-oxide (ITZO) as an active channel layer and multi-oxide structure of SiO (blocking layer)/Si-rich SiO (charge trapping layer)/SiON (tunneling layer) as a gate insulator. The insulators were deposited using inductive coupled plasma chemical vapor deposition, and during the deposition, the trap states of the Si-rich SiOx charge trapping layer could be controlled to widen the memory window with the gas ratio (GR) of SiH:NO, which was confirmed by fourier transform infrared spectroscopy (FT-IR).

Defect Analysis of Solution-Based Process CIGS Thin-Film Solar Cells Using Technology Computer-Aided Design.

Copper indium gallium sulfur selenide (Cu(InGa)SeS, CIGS) thin film solar cells are fabricated using a solution-based process, and their defect models are studied through a computer-aided design method. Cu(InGa)SeS is structured with a graded bandgap by controlling the ambient gas and precursor composition, during the fabrication process. The defects in the CIGS are modeled as two donor-like defects, which are differently distributed as per the CIGS grain size (large and small grains at upper and bottom layers, respectively), whereas those in the cadmium sulfide (CdS)/CIGS interface are modeled as a complex model of both donor- and acceptor-like defects in the CdS, near the interface.

Impedance Spectroscopy Analysis and Equivalent Circuit Modeling of Graphene Oxide Solutions.

The optical and electrical characteristics of a graphene oxide solution (GS) with different graphene oxide (GO) concentrations in de-ionized water are investigated via the electrochemical impedance spectroscopy (EIS) method. The measurement results produced by the EIS for the GS are represented with both Bode and Nyquist plots in a frequency range from 1 kHz to 10 MHz. Using these results, we develop an equivalent circuit model as a function of the GO concentration, representing the GS as a mixed circuit of two-dimensional (2D) GO dispersed in parallel in de-ionized (DI) water.

Method for Fabricating Textured High-Haze ZnO:Al Transparent Conduction Oxide Films on Chemically Etched Glass Substrates.

We developed a technique for forming textured aluminum-doped zinc oxide (ZnO:Al) transparent conductive oxide (TCO) films on glass substrates, which were etched using a mixture of hydrofluoric (HF) and hydrochloric (HCl) acids. The etching depth and surface roughness increased with an increase in the HF content and the etching time. The HF-based residues produced insoluble hexafluorosilicate anion- and oxide impurity-based semipermeable films, which reduced the etching rate.

A luminescent down-shifting and moth-eyed anti-reflective film for highly efficient photovoltaic devices.

Adhesive polydimethylsiloxane (PDMS) films were developed to increase the performance of photovoltaic devices. The films combined two separate features of moth-eye patterns to reduce the reflection of incident light at the film surface and luminescent down-shifting (LDS) CdZnS/ZnS-core/shell quantum dots (QDs) to convert ultraviolet (UV) radiation into visible light at 445 nm. The films were both flexible and self-adhesive, easily attachable to any surface of a solar cell module.

Scattering matrix analysis for evaluating the photocurrent in hydrogenated-amorphous-silicon-based thin film solar cells.

A scattering matrix (S-matrix) analysis method was developed for evaluating hydrogenated amorphous silicon (a-Si:H)-based thin film solar cells. In this approach, light wave vectors A and B represent the incoming and outgoing behaviors of the incident solar light, respectively, in terms of coherent wave and incoherent intensity components. The S-matrix determines the relation between A and B according to optical effects such as reflection and transmission, as described by the Fresnel equations, scattering at the boundary surfaces, or scattering within the propagation medium, as described by the Beer-Lambert law and the change in the phase of the propagating light wave.