Advantages of GaN-based LEDs with two-step graded AlGaN last quantum barrier
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Abstract
GaN-based multiple quantum well light-emitting diodes (LEDs) with the conventional, graded and two-step graded AlGaN last quantum barriers (LQBs) are investigated numerically. The simulation results show that the LED with two-step graded AlGaN LQB exhibits much higher light output power, lower turn-on voltage and smaller efficiency droop than those with the conventional and graded AlGaN LQBs. These improvements can be mainly attributed to the reduction of the electrostatic fields in the LQB and electron blocking layer caused by the mitigation of polarization effect with the redesigned LQB which enhances the electron confinement and improves the hole injection efficiency from p-type region greatly. Moreover, the two-step graded LQB not only improves the electron confinement of the EBL but also that of itself.
Keywords
Light-emitting diode GaN Efficiency droop Composition graded Last quantum barrier SimulationReferences
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