Power enhancement of 380 nm UV-LED with hexagonal pyramid structures by AlN sacrificial layer

Abstract

In this study, we propose to enhance an output power for 380 nm UV-LED with a hexagonal pyramid structures (HPS) on the interface of sidewall between AlGaN and AlN layers. The HPS are formed by inserting a 50 nm AlN as a sacrificial layer in n-AlGaN than using a selective wet etching process in KOH solution at 90 °C for 60 min. From the scanning electron microscope (SEM) image, the HPS can be clearly seen on the interface of AlGaN, the facet angles and the average of structure height of pyramid are 58° and 0.5-μm, respectively. According to the electroluminescent (EL) results, 12% enhancement of the light extraction efficiency can be expected in the UV-LED with HPS. Furthermore, we measured the output power at 20 mA between the UV-LED with and without HPS are 2.69 mW and 3.01 mW, respectively. As a result, the light extraction efficiency can be improved by this approach because of changing the routes of light reflection around the sidewall.