Investigation of the Carrier Distribution Characteristics in InGaN Multiple Quantum Wells by Using Dual-wavelength Light-emitting Diodes

The authors investigate the carrier transport and distribution characteristics of InGaN multiple-quantum-well (MQW) light-emitting diodes by comparing the electroluminescence (EL) and the photoluminescence (PL) spectra of dual-wavelength LEDs emitting around 440 nm and 460 nm. The PL spectra show distinctive peaks from both the 440-nm and the 460-nm emitting QWs whereas the EL spectra show only a dominant peak only from the 460-nm emitting QWs close to the p. side layers. This clearly reveals an inhomogeneous carrier distribution owing to inefficient hole transport. In addition, the effect of silicon doping on the carrier transport and distribution is investigated by comparing the EL spectra of LED structures with and without a silicon-doped barrier, and silicon doping at the barrier was found to affect the hole transport characteristics significantly. The experimental demonstrations are consistent with the simulation results for the carrier distribution in dual-wavelength MQW LEDs.