Marked Enhancement in the Efficiency of Deep-Ultraviolet AlGaN Light-Emitting Diodes by Using a Multiquantum-Barrier Electron Blocking Layer

We demonstrated high-efficiency 250-262 nm deep-ultraviolet (DUV) AlGaN multi-quantum well (MQW) light-emitting diodes (LEDs) fabricated on AlN/sapphire templates by introducing multiquantum-barrier (MQB) electron-blocking layers (EBLs). A marked enhancement in efficiency, by as much as 2.7 times, was observed for a 250 nm AlGaN LED by replacing the usual single-barrier'' EBL with a MQB-EBL. The maximum external quantum efficiencies and output powers of LEDs with MQB-EBLs measured under room temperature (RT) cw operation were 1.18% and 4.8 mW, and 1.54% and 10.4 mW, for the 250 nm and 262 nm LEDs, respectively, which are the highest values ever reported. (C) 2010 The Japan Society of Applied Physics