We demonstrate the optoelectrical characteristics of thick well short-period InGaN/GaN multiple-quantum-well (MQW) light-emitting diodes (LEDs) with H<sub>2</sub> in GaN barrier spacer layer. Introducing ramped H<sub>2</sub> in the GaN barrier spacer layer creates a wide range of severe well thickness variation randomly distributed in the thick InGaN well. The thickness-fluctuated InGaN well would effectively increase the carrier concentration in the region of the thick InGaN well region during the current injection. Moreover, the ramped H<sub>2</sub> in GaN barrier spacer layer would improve the interface and crystal quality of thick well short-period InGaN/GaN MQWs LEDs. Therefore, compared with traditional long-period InGaN/GaN MQW LEDs, thick well short-period InGaN/GaN MQW LEDs with fluctuated InGaN well thickness enhance output power (25.6% at 20 mA) and improve efficiency droop from 55.0% to 36.7%.
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