Efficiency Enhancement of InGaN LEDs With an n-Type AlGaN/GaN/InGaN Current Spreading Layer

This letter reports an InGaN light-emitting diode (LED) structure that has an n-type Al
_0.1
Ga
_0.9
N/GaN/In
_0.06
Ga
_0.94
N current spreading layer under its multiple-quantum-well active region. As indicated by simulation, the Al
_0.1
Ga
_0.9
N/GaN/In
_0.06
Ga
_0.94
N heterostructure induces a higher electron concentration than an n-AlGaN/GaN cladding layer and an n-GaN/InGaN current spreading layer that are used in conventional LEDs. As a result, the proposed n-type spreading layer is expected to alleviate current crowding and improve external quantum efficiency. Experimentally, the light output uniformity across the chips is greatly improved. The output power and wall-plug efficiency are enhanced by about 18.2% and 22.2% at an injection current of 350 mA for the LEDs employing the new double-heterostructure current spreading layer.