Evaluation of Light Extraction Efficiency of GaN-Based Nanorod Light-Emitting Diodes by Averaging over Source Positions and Polarizations

Han-Youl Ryu

doi:10.3390/cryst8010027

Abstract

Light extraction efficiency (LEE) of GaN-based nanorod blue light-emitting diode (LED) structures is investigated using finite-difference time-domain (FDTD) simulations. When the LEE is calculated for different source positions inside the nanorod, the LEE is found to depend strongly on the source positions and the polarization directions for each source position, implying that the LEE of nanorod LED structures should be evaluated by averaging over source positions and polarization directions for determining the LEE accurately. The averaged LEE of nanorod LED structures is simulated as the radius, the p-GaN thickness, and the n-GaN thickness is varied, and the optimum structural parameters can be obtained. In addition, the far-field pattern is simulated when considering the averaging effects, and the circularly symmetric and uniform emission distribution is obtained.

Highlights

Since the first demonstration of GaN-based light-emitting diodes (LEDs) in the early 1990s, there has been remarkable progress in GaN-based LEDs over the last two decades [1,2,3,4]
We investigate the dependence of positions and polarization of a dipole source on information on the Light extraction efficiency (LEE), Purcell factors, and emission patterns of nanorod LEDs
We investigate the dependence of positions and polarization of a dipole source on nanorod LED is determined by averaging over the active area and the polarization directions, which the LEE and emission patterns of nanorod LED structures using finite-difference time-domain (FDTD) simulations

Summary

Introduction

Since the first demonstration of GaN-based light-emitting diodes (LEDs) in the early 1990s, there has been remarkable progress in GaN-based LEDs over the last two decades [1,2,3,4]. In the most cases placed usually at the center of nanorod structures have been reported, which may provide incorrect of FDTD simulation works on nanorod LEDs, simuilation results for only a single dipole source information on the LEE, Purcell factors, and emission patterns of nanorod LEDs. placed usually at the center of nanorod structures have been reported, which may provide incorrect. We investigate the dependence of positions and polarization of a dipole source on nanorod LED is determined by averaging over the active area and the polarization directions, which the LEE and emission patterns of nanorod LED structures using FDTD simulations. The far-field pattern (FFP) data from the is calculated as the radius, the p-GaN thickness, and the n-GaN thickness is varied, and the optimum nanorod LED are presented by averaging the FFP over dipole source positions and polarization nanorod LED structure for high LEE is discussed. LED are presented by averaging the FFP over dipole source positions and polarization directions

Methods

Results and Discussion

Conclusions