Double heterostructure ultraviolet light emitting diodes with nanometer scale compositionally inhomogeneous active regions

We report on the fabrication and evaluation of flip‐chipped double heterostructure UVLEDs operating at 320 nm that employ a bulk (80nm) AlGaN active region containing nanoscale compositional inhomogeneities (NCI), deposited by plasma‐assisted molecular beam epitaxy. The devices were deposited on AlGaN templates grown by hydride vapor phase epitaxy and contain electron and hole injection layers grown by metalorganic chemical vapor deposition. A packaged, 300 μm x 300 μm device with 3% internal quantum efficiency has a peak output power of 0.56 mW at 90 mA DC current that corresponds to an external quantum efficiency of 0.15%. Nearly constant external quantum efficiency is observed for DC current density up to 100 A/cm2, suggesting that the NCI regions effectively suppress the deleterious effects of polarization fields at low injection currents that should inhibit radiative recombination in double heterostructure devices. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)