Thermal analysis and design of GaN-based LEDs for high power applications

In this paper, a thermal analysis was made on blue and white GaN-based LEDs. The thermal analysis consists of experimental temperature measurements and finite element calculations on the LED chips and surface of epoxy package. The direct on-chip temperature measurement using a nematic liquid crystal resulted in a hot spot with a transition boundary of 43 °C in a range of about 450 to 500 μm under a forward voltage of 3.9 V. The surface temperature of the epoxy package was measured as a function of input power and it exhibits a linear relationship. The finite element method was used for the calculation of temperature distributions for samples and the simulated data showed good agreement with the experimental results.