Efficiency Enhancement of InGaN MQW LED Using Compositionally Step Graded InGaN Barrier on SiC Substrate

In this paper, we designed and simulated a silicon carbide (SiC) technology, InGaN multiple quantum well (MQW) light-emitting diode (LED) using a compositionally step graded (CSG) InGaN barrier in the active region. The optical power, internal quantum efficiency (IQE), and carrier distribution profile in the device are theoretically studied by Sentaurus TCAD simulation. The CSG InGaN barrier LED shows substantial improvement in IQE when comparing the structures with conventional GaN barrier or InGaN barrier. This improvement is mainly due to the enhanced hole transportation/injection and modified band bending by polarization effect. The results show an excellent agreement with the experimental data. Moreover, the lattice-matched SiC substrate technology increases the radiative recombination rate in the InGaN MQW LEDs. The optical output and peak IQE obtained is 62 mW and 76.5%, respectively, for the proposed LED emitting at 450 nm wavelength at an injection current of 200 mA. This enhanced performance of the SiC technology makes it a good alternative for sapphire substrate in commercial lighting applications.