Modeling of Junction Temperature and Current Flow in High Power InGaN/GaN Light Emission Diodes Using Finite Element Methods

InGaN/GaN LEDs offer important lighting devices for human livings. These devices have high efficiency and lifetimes at low injection power but so far show degradation under high injection conditions. Current spreading and heat dissipation are key reasons for degradation under high power operation. In this paper, we have developed a three-dimensional (3-D) finite element method (FEM) to examine the heat generation and dissipation and a two-dimensional (2D) Finite element Poisson and drift-diffusion solver for the analysis of current spreading. As we know, the junction temperature plays an important role to the performance of the LED, and it will influence the optical performance. Therefore, the discussion of different surface current density and sapphire width will be considered in this paper. We examine how current flow can be altered by careful design of the LEDs. Results for a conventional LED and an LED with ion-implantation to improve current flow are presented. Our simulations show that improved device design based on modifying current flow paths can improve the device operation.