Improved performance of InGaN/GaN Near-UV light-emitting diodes with staircase hole injector

Abstract

We report the enhanced performance of near-ultraviolet (NUV) InGaN/GaN multiple quantum-well (MQW) light-emitting diodes (LEDs) with a staircase hole injector (SHI). Simulation results indicate that the internal electrostatic field in the QW of the LED-SHI is decreased owing to the reduced sheet charge density at the interface between QW and quantum barrier (QB) caused by the smaller In content difference. Additionally, the SHI structure in the QBs suppresses the ballistic or quasi-ballistic hole transport, thus enhancing efficient hole injection into the QWs. The radiative output power of an LED-SHI is increased by 25.3% at 300 mA over that of conventional LEDs with GaN QBs. The droop of internal quantum efficiency (IQE) an LED-SHI at 300 A·cm−1 is 6.1%, while the LED with GaN QBs has an IQE droop of 17.7%. The reduced IQE droop and increased radiative output power in the LED-SHI is attributed to the reduced hole overflow, increased hole injection into the MQW and the decreased electrostatic field in the MQWs. The results show that the SHI structure in the LED is promising for improved performance in high-power GaN-based NUV LEDs.

Improved Performance of InGaN/AlGaN Multiple‐Quantum‐Well Near‐UV Light‐Emitting Diodes with Convex Barriers and Staggered Wells

“…Up to now, some strategies for regulating band of QW and quantum barrier have been reported to ameliorate polarized electric field in MQWs active region and reduce the quantum confined stark effect for increasing the overlap of electron and hole wave functions: such as dual‐layer staggered quantum barrier with the graded Al composition, [ 17 ] three‐layer staggered quantum barrier, [ 18 ] dual‐triangle quantum barriers, [ 19 ] stepped quantum barrier with the graded In composition, [ 20,21 ] concave quantum barrier, [ 22 ] partial‐grade barriers, [ 23 ] InGaN barriers, [ 24 ] adjusting the width of QWs or barriers [ 25,26 ] ; Besides, many proposals for optimizing QW structure have been reported: triangular QWs, [ 27 ] staggered InGaN QWs, [ 28–31 ] gradually varying indium content QWs, [ 32 ] trapezoidal QWs, [ 33,34 ] step‐stage QWs, [ 35 ] zigzag‐shaped QWs, [ 36 ] and W‐shaped QWs. [ 37 ] This method uses a variety of ways for designing the energy band of QWs and barriers to ameliorate carrier transport and distribution as well as to obtain a marked advanced radiative recombination rate.…”