김재균 교수

We discuss the influence of V-pits and their energy barrier, originating from its facets of (101¯1) planes, on the luminescence efficiency of InGaN LEDs. Experimental analysis using cathodoluminescence (CL) exhibits that thin facets of V-pits of InGaN quantum wells (QWs) appear to be effective in improving the emission intensity, preventing the injected carriers from recombining non-radiatively with threading dislocations (TDs). Our theoretical calculation based on the self-consistent approach w

We report the effect of V-shaped pit size, inverted hexagonal pits embedded in InGaN multiple quantum well, on the reverse leakage current of InGaN light-emitting diodes (LEDs). It was found that the reverse leakage current of InGaN LEDs with larger V-shaped pits is significantly reduced from 1.80 mA down to 3.84 nA at -30 V by several orders of magnitude. We claim that this improvement is accounted for increased Poole-Frenkel barrier height of carrier trapped at the deep centers via enlarged V-

Solution-processed indium gallium tin oxide (InGaSnO, IGTO) thin film transistors (TFTs) are investigated as promising low-cost and stable materials for high-performance amorphous oxide semiconductor (AOS)-based TFTs in display applications. After tailoring the metal cation composition in IGTO thin films, the IGTO (7:1:1) AOS TFT shows a saturation mobility and current on/off ratio of 2.13 cm2 V–1 s–1 and 2.55 × 107, superior to the IGZO TFT. It was found that the threshold voltage (Vth) shifts

To achieve both high structural integrity and excellent ion transport, designing ion gel polymer electrolytes (IGPEs) composed of an ionic conducting phase and a mechanical supporting polymer matrix is one of the promising material strategies for the development of next-generation all-solid-state energy storage systems. Herein, we prepared an IGPE thin film, in which an ion-diffusing phase containing ionic liquids and lithium salts was bicontinuously intertwined with a cross-linked epoxy phase,

Abstract New ionic‐gel polymer electrolytes (IGPEs) are designed for use as electrolytes for all‐solid‐state supercapacitors (ASSSs) with excellent deformability and stability. The combination of the photochemical reaction‐based polymer matrix, weak‐binding lithium salt with ionic liquid, and ion dissociating solvator is employed to construct the nano‐canyon structured IGPE with high ionic conductivity (σ DC = 1.2 mS cm −1 at 25 ° C), high dielectric constant (ε s = 131), and even high mechanica

We report the characteristics of forward tunneling current in InGaN/GaN multiple quantum well light-emitting diodes (LEDs) grown on Si (111) substrate. Temperature-variable current-voltage (I–V) measurement from 80 K to 400 K reveals that forward current regimes can be distinguished by corresponding slopes in semi-logarithmic plot, which are associated with different forward conduction mechanisms of InGaN LED. Temperature-insensitive tunneling behavior appears to be dominant at low current injec

We investigate the reverse leakage characteristics of InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) grown on Si (111) substrate by metal-organic chemical vapor deposition. The reverse leakage characteristics of InGaN/GaN LED on silicon are measured as low as ~10 nA at -5 V and -10 μA at -15 V. Temperature-dependent current-voltage ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML"

Stretchable sensors have been widely investigated and developed for the purpose of human motion detection, touch sensors, and healthcare monitoring, typically converting mechanical/structural deformation into electrical signals. The viscoelastic strain of stretchable materials often results in nonlinear stress-strain characteristics over a broad range of strains, consequently making the stretchable sensors at the body joints less accurate in predicting and recognizing human gestures. Accurate re

We report forward tunneling characteristics of InGaN/GaN blue light emitting diodes (LEDs) on freestanding GaN detached from a Si substrate using temperature-dependent current⁻voltage (<i>T-I-V</i>) measurements. <i>T-I-V</i> analysis revealed that the conduction mechanism of InGaN/GaN LEDs using the homoepitaxial substrate can be distinguished by tunneling, diffusion and recombination current, and series resistance regimes. Their improved crystal quality, inherited from the nature of homoepitax

We report a facile and versatile approach for fabricating large-area organic thin film transistor (OTFTs) arrays via a fluidic channel method. Evaporation-controlled fluidic channel-containing organic semiconductors easily produce large-area organic single-crystalline thin films in a quite uniform manner. The unidirectional movement of the meniscus and the subsequent film growth via solvent evaporation inside the fluidic channel correspond to the simulation based on the finite element method. Ut

The nature of reverse leakage current characteristics in InGaN/GaN blue light emitting diodes (LEDs) on freestanding GaN crystals detached from a Si substrate is investigated for the first time, using temperature-dependent current-voltage (T-I-V) measurement. It is found that the Si-based homoepitaxial InGaN/GaN LEDs exhibit a significant suppression of the reverse leakage current without any additional processes. Their conduction mechanism can be divided into variable-range hopping and nearest

Abstract We investigated the electrical properties and operational stability of amorphous indium-tin-zinc-oxide (a-ITZO) thin-film transistors (TFTs). We fabricated the a-ITZO TFTs using deposition by radio frequency sputtering at room temperature followed by a rapid thermal annealing (RTA) process at different temperatures and oxygen pressure ( P O2 ). This is a more practical annealing route compared to a conventional furnace. Based on film densification and oxygen vacancy optimization, the a-