Robust 285 nm Deep UV Light Emitting Diodes over Metal Organic Hydride Vapor Phase Epitaxially Grown AlN/Sapphire Templates

Significant progress has been made in the development of III–nitride deep UV light emitting diodes (LEDs) grown on sapphire substrates using AlGaN multiple quantum well (MQW) active regions. This progress was largely based on the advancements integrated in the first reported deep UV LEDs demonstrating sub-milliwatt output power. 1) The key to the success of these devices was based on three technical advancements. First was the use of pulsed atomic layer epitaxy (PALE) to improve the quality of the buffer AlN layer. 2,3) PALE deposited AlxGa1� xN/AlyGa1� yN shortperiod superlattices were also inserted between the buffer AlN and the n-contact AlGaN layer to control the thinfilm stress, thereby mitigating epilayer cracking. 4) Finally, a p-GaN/p-AlGaN heterojunction contact layer was used to improve hole injection. 5) The same technical approaches were subsequently used by Zhang et al. to commercialize deep UV LEDs. 6)