GaN/GaInN asymmetric multiple quantum well light-emitting diodes with varying potential barrier thicknesses (5 and 15 nm) are grown by using metal organic chemical vapor deposition. The narrow barrier structure improves the performance of the device, including the super-linear increase of electroluminescence integral intensity, the mitigation of efficiency droop at high current density, the reduction of wavelength drift, the reduction of forward voltage, and the improvement of wall-plug efficiency. This is due to the narrowing of the thickness of the quantum barrier, which results in the smaller electric field among the quantum well, the weakening of the quantum confinement Stark effect, the more uniform distribution of carriers across the active region of the device, and the suppression of electron leakage.
The physical mechanism of improving the photoelectric performance of InGaN/AlGaN‐based near UV light‐emitting diode (LED) with convex quantum barrier and staggered quantum well (QW) is studied by numerical simulation. The simulation results indicate that the voltage–current characteristics of the LED structure with convex quantum barrier and staggered QW are effectively improved compared with the traditional multiple quantum well (MQW) structure, and its electroluminescence (EL) intensity and light output power are significantly improved. The main physical mechanisms are: on the one hand, the convex quantum barrier with a lower average Al component can reduce the polarization electric field at the interface between the quantum barrier and QW as well as the effective potential barrier of holes, improve the spatial separation of electron and hole wave functions, promote the injection efficiency of carriers, and improve the uniformity of carrier distribution in the MQWs active region; On the other hand, staggered QWs can provide stronger carrier confinement effect and further increase the overlap of electron and hole wave functions, so as to improve the carrier radiative recombination efficiency; In a word, this work provides a valuable reference for obtaining high‐performance near‐ultraviolet LED.
Herein, a novel AlGaN‐based multiple quantum well (MQW) deep UV light‐emitting diode (DUV‐LED) structure with two parts linearly graded barriers is presented. The simulation result shows that at a current of 50 mA, the light output power of the DUV‐LED with two parts linearly graded barrier MQWs has significant improvement as compared to stationary barriers. The electroluminescence spectrum and radiative recombination rate of novel DUV‐LEDs are also larger more than twice that of the conventional QW structure. The reason is that the injection efficiency of holes is increased which helps improve the hole and electron concentration in the active area. Meanwhile, the electric field is also decreased by using two parts linearly graded quantum barriers, and according to reduce the electric field the quantum‐confined Stark effect and the bend of the energy band get relieved.
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