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.

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.