Jih-Yuan Chang

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Some specific designs on the electron blocking layer (EBL) of blue InGaN LEDs are investigated numerically in order to improve the hole injection efficiency without losing the blocking capability of electrons. Simulation results show that polarization-induced downward band bending is mitigated in these redesigned EBLs and, hence, the hole injection(More)
The advantages of blue InGaN light-emitting diodes (LEDs) with AlGaN barriers are studied numerically. The performance curves, energy band diagrams, electrostatic fields, and carrier concentrations are investigated. The simulation results show that the InGaNAlGaN LED has better performance than its conventional InGaNGaN counterpart owing to the increase of(More)
In blue InGaN light-emitting diodes (LEDs), the intuitive approaches to suppress Auger recombination by reducing carrier density, e.g., increasing the number of quantum wells (QWs) and thickening the width of wells, suffer from nonuniform carrier distribution and more severe spatial separation of electron and hole wave functions. To resolve this issue, LED(More)
The advantages of blue InGaN light-emitting diodes with low bandgap energy and polarization-matched AlGaInN barriers are demonstrated numerically. Simulation results show that, besides the common benefit of enhanced electron-hole spatial overlap in the quantum well from the polarization-matched condition, the lower bandgap energy barriers can have(More)
Monolithic stacked InGaN light-emitting diode (LED) connected by a polarization-enhanced GaN/AlN-based tunnel junction is demonstrated experimentally in this study. The typical stacked LEDs exhibit 80% enhancement in output power compared with conventional single LEDs because of the repeated use of electrons and holes for photon generation. The typical(More)
The impact of the polarization compensation InGaN interlayer between the heterolayers of Ga-face GaN/InGaN p-i-n solar cells is investigated numerically. Because of the enhancement of carrier collection efficiency, the conversion efficiency is improved markedly, which can be ascribed to both the reduction of the polarization-induced electric field in the(More)
The effect of using chirped multiple quantum-well (MQW) structures in InGaN green light-emitting diodes (LEDs) is numerically investigated. An active structure, which is with both thick QWs with low indium composition on the p-side and thin QWs with high indium composition next to the n-region, is presented in this study. The thickness and indium(More)
To illustrate nonlinear-optical applications of germanium dioxide (GeO(2)) glass optical fibers, we have demonstrated efficient single-pass Raman generation in a GeO(2) fiber. We also measured the chromatic dispersion of high-silica glass (SiO(2)) single-mode optical fibers by using a GeO(2) fiber Raman laser.
The phenomenon of efficiency droop in blue InGaN light-emitting diodes (LEDs) is studied numerically. Simulation results indicate that the severe Auger recombination is one critical mechanism corresponding to the degraded efficiency under high current injection. To solve this issue, LED structure with thin AlGaN barriers and without the use of an AlGaN EBL(More)
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