A modified ABC model in InGaN MQW LED using compositionally step graded Alternating Barrier for efficiency improvement. (August 2016) - Prajoon, P.
Abstract: In this paper, Multiple Quantum Well (MQW) Light-Emitting Diodes (LEDs) with compositionally step graded (CSG) Alternating Barriers (AB) of InGaN-AlGaN with p-doped GaN barrier is designed and analysed. The improved crystal structure and modified band bending in the device enhances the carrier confinement and diminishes the polarization-related efficiency reduction. Furthermore, the good crystalline quality increases the hole injection and transportation; this significantly improves the radiative recombination rate and reduces the non-radiative recombination as well as carrier leakage out of the active region. Simulation result show mitigated efficiency droop of 3% and light output power of 1500 mW at the injection current of 500 mA. A modified ABC model is also developed to model the carrier leakage mechanism at high injection current density. In the model, total carrier leakage currents from the active region due to thermionic emission and electron overflow at high injection current are considered. Also, the obtained result of the modelled conventional LED shows a good fit with experimental data. Moreover, the SiC substrate technology in the design is attributed with improved crystal structure, reduced polarization effect and thermal conductivity, which improve the optical performance of the device. Highlights: InGaN MQW LED with step graded alternating barrier to mitigate the efficiency droop effect at high injection current. SiC substrate technology diminishes the effect of lattice mismatching problem in InGaN LED. Carrier leakage mechanism out of the active region is modelled by including thermionic emission and overflow. Efficiency droop is mitigated to 3% and achieved an optical output power of 1500 mW at the injection current of 500 mA.