Simulation of an Improved Design for n‐Electrode with Holes for Thin‐GaN Light‐Emitting Diodes

Farn-Shiun Hwu

doi:10.1155/2013/805361

Abstract

A novel design is proposed for n‐electrode with holes to be applied in Thin‐GaN light‐emitting diodes (LEDs). The influence of the n‐electrode with holes on the thermal and electrical characteristics of a Thin‐GaN LED chip is investigated using a three‐dimensional numerical simulation. The variations in current density and temperature distributions in the active layer of n‐electrodes both with and without holes are very tiny. The percentages of light output from these holes are 29.8% and 38.5% for cases with 5 μm holes and 10 μm holes, respectively; the side length of the n‐electrode (L) is 200 μm. Furthermore, the percentage increases with the size of the n‐electrode. Thus, the light output can be increased 2.45 times using the n‐electrode with holes design. The wall‐plug efficiency (WPE) can also be improved from 2.3% to 5.7%. The most appropriate n‐electrode and hole sizes are determined by WPE analysis.

Highlights

Light-emitting diodes have many advantages over conventional light sources, such as their narrow spectrum, long lifetime, and good mechanical stability [1, 2]
The current distribution in an light-emitting diodes (LEDs) chip is usually estimated from the light output [8, 10] and is affected by the material properties of the chip, as well as the size and pattern of the electrode [8, 10,11,12]
The electrical characteristics of the LEDs will not be affected by this slight temperature difference

Summary

Introduction

Light-emitting diodes have many advantages over conventional light sources, such as their narrow spectrum, long lifetime, and good mechanical stability [1, 2]. The continuity equation for electronic transport can be used in three-dimensional models to simulate the electric potential and current in lateral-injection LED chips This has proven to be much more economical than other methods [9, 17]. A numerical model, which considered the thermal effect, was proposed for simulating a vertical LED chip [22]. We modify the 3D numerical model developed in our previous work [22] to simulate the influence of the n-electrode with holes This method is used to investigate the thermal and electrical characteristics of ThinGaN LED chips operating under high-power conditions. The wallplug efficiency (WPE) is discussed in our numerical model

Numerical Simulation

Results and Discussion

Conclusions