Light extraction enhancement of light-emitting diodes by nanopillar hierarchical structures

Controllable Design of Minority Carrier Diffusion in npn Devices for Enhancing Er3+-Related Electroluminescence

“…The difference between the optical power density obtained by experience and the theoretical maximum optical power density mainly comes from several aspects: (i) when calculating the theoretical maximum optical power density, the light extraction efficiency is assumed to be 100%, but the actual light extraction efficiency of semiconductor LEDs is generally low. 40 To estimate the light extraction efficiency, the refractive index n of the AZO: Er film and ITO electrode are tested by an ellipsometer. n AZO: Er and n ITO are 1.93 and 1.20 at 1540 nm, respectively.…”

Investigation into the Effects of Cross-Sectional Shape and Size on the Light-Extraction Efficiency of GaN-Based Blue Nanorod Light-Emitting Diode Structures

“…Nanorod LED structures, with dimensions of a few hundred nanometers in diameter and a few micrometers in length, are expected to exhibit high LEE because the TIR can be easily spoiled in wavelength-sized structures. Several previous studies have demonstrated the enhancement of LEE in GaNbased nanorod LED structures [37][38][39][40][41].…”

“…Because the FDTD method numerically solves four Maxwell's equations without any assumptions or approximations, it can provide accurate simulation results of the optical properties in photonic devices. Therefore, studies on the LEE and light-emitting pattern of micro/nano-LED structures have been frequently conducted using the FDTD method [28,31,[40][41][42][43][44][45][46].…”

“…Because of the small chip dimensions on the wavelength scale, the LEE in the nanorod LED structure depends on the dipole source location and polarization direction [46]. However, most previous studies on FDTD simulations of nanorod LED structures reported simulation results for only a single dipole source, which was typically placed at the center of the nanorod structure [40][41][42][43][44][45]. This assumption may not provide realistic results for the LEE and FFP of nanorod LEDs.…”