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Open Access Nano Express

Large enhancement of light extraction efficiency in AlGaN-based nanorod ultraviolet light-emitting diode structures

Han-Youl Ryu

Author Affiliations

Department of Physics, Inha University, Incheon 402-751, Korea

Nanoscale Research Letters 2014, 9:58  doi:10.1186/1556-276X-9-58

Published: 4 February 2014

Abstract

Light extraction efficiency (LEE) of AlGaN-based nanorod deep ultraviolet (UV) light-emitting diodes (LEDs) is numerically investigated using three-dimensional finite-difference time-domain simulations. LEE of deep UV LEDs is limited by strong light absorption in the p-GaN contact layer and total internal reflection. The nanorod structure is found to be quite effective in increasing LEE of deep UV LEDs especially for the transverse magnetic (TM) mode. In the nanorod LED, strong dependence of LEE on structural parameters such as the diameter of a nanorod and the p-GaN thickness is observed, which can be attributed to the formation of resonant modes inside the nanorod structure. Simulation results show that, when the structural parameters of the nanorod LED are optimized, LEE can be higher than 50% and 60% for the transverse electric (TE) and TM modes, respectively. The nanorod structure is expected to be a good candidate for the application to future high-efficiency deep UV LEDs.

PACS

41.20.Jb; 42.72.Bj; 85.60.Jb

Keywords:
Ultraviolet light-emitting diode; Nanorod; AlGaN; Light extraction efficiency; Finite-difference time-domain method