Carrier-density-dependent recombination rates in GaInN/GaN QW LED structure with V-pit and threading dislocation

摘要

We model carrier-density-dependent radiative and non-radiative recombination rates in an InGaN/GaN quantum well structure containing a V-pit and a threading dislocation. It is known that the threading dislocation acts as the non-radiative recombination center, leading to the reduction of carriers which can participate in the radiative recombination. On the other hand, the quantum well structure grown on the sidewalls of V-pit, formed by the strain relying on In/Ga contents and connected with threading dislocation directed along the polar direction, plays a role of energy barriers to prevent quantum well in-plane charge carriers from flowing to the non-radiative recombination center, i.e., the threading dislocation. Therefore, such V-pits can enhance the internal quantum efficiency in the InGaN/GaN quantum well light emitting diode (LED). However, the explicit model of the V-pit and the threading dislocation coupled to three dimensional electronic states has rarely been studied. We take into account those defects by including their potentials in a system Hamiltonian. It can describe the electronic states of in-plane quantum well, in which a V-pit and a threading dislocation are positioned. Here we show that charged carriers are more distributed away from the threading dislocation by having the V-pit, and it leads to the reduction of carrier losses to the non-radiative recombination and hence the enhancement of radiative recombination rate. Their effects on the recombination rates depend on injected carrier densities. We also discuss mid-gap defect states, which may be generated due to the threading dislocation and the V-pit.