# Reflective Metal/Semiconductor Tunnel Junctions for Hole Injection in AlGaN UV LEDs

## TL;DR

This paper demonstrates that reflective aluminum layers can enable efficient hole injection in AlGaN UV LEDs through nanoscale polarization engineering, leading to high power density and efficiency.

## Contribution

The study introduces a novel metal/semiconductor tunnel junction using reflective aluminum for hole injection in AlGaN UV LEDs, improving efficiency and power density.

## Key findings

- Achieved 2.65% external quantum efficiency
- Measured 83.7 W/cm2 power density at 1200 kA/cm2
- Confirmed efficient hole injection via light emission at 326 nm

## Abstract

In this work, we investigate the use of nanoscale polarization engineering to achieve efficient hole injection from metals to ultra-wide band gap AlGaN, and we show that UV-reflective aluminum (Al) layers can be used for hole injection into p-AlGaN. The dependence of tunneling on the work function of the metal was investigated, and it was found that highly reflective Al metal layers can enable efficient hole injection into p-AlGaN, despite the relatively low work function of Al. Efficient tunneling hole injection was confirmed by light emission at 326 nm with on-wafer peak external quantum efficiency and wall-plug efficiency of 2.65% and 1.55%, respectively. A high power density of 83.7 W/cm2 was measured at 1200 kA/cm2. The metal/semiconductor tunnel junction structure demonstrated here could provide significant advantages for efficient and manufacturable device topologies for high power UV emitters.

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Source: https://tomesphere.com/paper/1705.08414