Design and performance of nitride-based UV LEDs

In this paper, we overview several of the critical materials growth, design and performance issues for nitride-based UV (<400 nm) LEDs. The critical issue of optical efficiency is presented through temperature-dependent photoluminescence studies of various UV active regions. These studies demonstrate enhanced optical efficiencies for active regions with In-containing alloys (InGaN, AlInGaN). We discuss the trade-off between the challenging growth of high Al containing alloys (AlGaN, AlGaInN), and the need for sufficient carrier confinement in UV heterostructures. Carrier leakage for various composition AlGaN barriers is examined through a calculation of the total unconfined carrier density in the quantum well system. We compare the performance of two distinct UV LED structures: GaN/AlGaN quantum well LEDs for λ<360 nm emission, and InGaN/AlGaInN quantum well LEDs for 370 nm<λ<390 nm emission.