Carrier Transport Study of TMIn-Treated InGaN LEDs by Using Quantum Efficiency and Time-Resolved Electro-Luminescence Measurements

Abstract

The aim of this study is to determine the emission and carrier transport characteristics of Trimethylindium (TMIn)-treated InGaN green light emitting diodes (LEDs) by using quantum efficiency and time-resolved electro-luminescence measurements. As TMIn treatment time increased, a more homogeneous indium composition and low V-shaped defect density lead to slightly blue-shifted peak position, narrower spectrum width, and better luminescence efficiency. In addition, the ns-scale response time shows efficient carrier injection and carrier transport. The shorter response times of the longer-TMIn-treated LED suggest that a lower V-shaped density is beneficial to carrier injection into the quantum wells and that a slight carrier localization helps carrier recombination. Furthermore, a μs-scale decay time represents inefficient carrier recombination in the active region. The longer the TMIn treatment time, the shorter the response time, the faster the radiative decay rate, and the slower the nonradiative decay rate. With a forward applied voltage, lower V-shaped defect density, un-reduced polarization field, carrier delocalization, and weaker Auger recombination in the TMIn-treated samples lead to the inevitable efficiency droop. The resulting recombination dynamics are correlated with the device characteristics and performance of the TMIn-treated LEDs. The research results provide important information to solve the efficiency droop of LEDs.