Electroluminescence Study of Inhomogeneous Carrier Distribution in InGaN Multiple-quantum-well Light-emitting Diode Structures

Due to the low hole mobility in InGaN materials, hole transport in InGaN/GaN multiple-quantum-well (MQW) structures should be quite inefficient, which could result in an inhomogeneous distribution of hole carriers in the MQWs. in this work, the author investigates the carrier distribution and the transport in dual-wavelength InGaN MQW light-emitting diode (LED) structures emitting around 940 nm and 460 urn. Electroluminescence (EL) spectroscopy has been performed to study the carrier transport characteristics for two LEDs having different MQW layer structures. The inhomogeneous hole carrier distribution is clearly demonstrated from the EL spectra, which shows that most of the emitted light comes from the 460-nm-emitting QWs positioned near the p-side layers for both LED structures. In addition, the hole carrier transport problem and the inhomogeneous hole distribution are also confirmed by simulations of the carrier distribution and the radiative recombination in the studied MQW LED structures.