Enhanced vertical emission from GaN based light emitting diode with ZnO nanorod arrays produced by hydrothermal method

In this study, we analyzed the modulated light output from the GaN based light emitting diodes (LEDs) with the incorporation of ZnO nanorod by hydrothermal method. With the ZnO nanorod, the light output from the LEDs increased by 20.2% and more interestingly, output power was more concentrated in a smaller escape cone of~ �� =30 o than that of conventional LEDs with a cone of~�� =42 o . Surface damaging of LEDs was also avoided by the low temperature hydrothermal growth of ZnO nanorod arrays. Experiments and Discussion- The epitaxial layers of the InGaN/GaN multiple quantum well (MQW) LEDs were grown on c-plane sapphire substrate by MOCVD technique. The structure is composed of a 50-nm-thick GaN buffer layer, a 3-µm-thick Si-doped GaN layer (3×10 17 cm -3 ), an undoped InGaN/GaN multiple quantum