Enhanced Light Extraction in Tunnel Junction Enabled Top Emitting UV LEDs

TL;DR

This paper presents a novel surface roughening technique combined with tunneling contacts to significantly improve light extraction efficiency in UV LEDs, achieving over 40% enhancement without complex manufacturing.

Contribution

It introduces a surface roughening method using self-assembled Ni nano-clusters for UV LEDs, enhancing efficiency without complex fabrication.

Findings

External quantum efficiency increased by over 40%.

Surface roughening effectively reduces absorption losses.

Method enables high-efficiency UV LEDs without flip chip bonding.

Abstract

The efficiency of ultra violet LEDs is critically limited by the absorption losses in p-type and metal layers. In this work, surface roughening based light extraction structures are combined with tunneling-based top-contacts to realize highly efficient top-side light extraction efficiency in UV LEDs. Surface roughening of the top n-type AlGaN contact layer is demonstrated using self-assembled Ni nano-clusters as etch mask. The top surface roughened LEDs were found to enhance external quantum efficiency by over 40% for UV LEDs with a peak emission wavelength of 326 nm. The method described here can enable highly efficient UV LEDs without the need for complex manufacturing methods such as flip chip bonding.