Enhancement of blue InGaN light-emitting diodes by using AIGaN increased composition-graded barriers

The characteristics ofnitride-based blue light-emitting diodes （LEDs） with A1GaN composition-graded barriers are analyzed numerically. The carrier concentrations in the quantum wells （QWs）, the energy band di- agrams, the electrostatic fields, and the light output power are investigated by APSYS software. The simulation results show that the LED with AlGaN composition-graded barriers has a better performance than its AlGaN/InGaN counterpart owing to the increase of hole injection and the enhancement of electron confinement. The simulation results also suggest that the output power is enhanced significantly and the efficiency droop is markedly improved when the AIGaN barriers are replaced by AlGaN composition-graded barriers.