Study of dual-blue light-emitting diodes with asymmetric AIGaN graded barriers

A dual-blue light-emitting diode （LED） with asymmetric A1GaN composition-graded barriers but without an AlGaN electron blocking layer （EBL） is analyzed numerically. Its spectral stability and efficiency droop are improved compared with those of the conventional InGaN/GaN quantum well （QW） dual-blue LEDs based on stacking structure of two In0.18Ga0.szN/GaN QWs and two In0.12Ga0.88N/GaN QWs on the same sapphire substrate. The improvement can be attributed to the markedly enhanced injection of holes into the dual-blue active regions and effective reduction of leakage current.