Structural analysis and modelling of packaged light emitting devices by thermal transient measurements at multiple boundaries

The paper presents theoretical and practical steps needed for modelling the electric, optical and thermal behaviour of high power LEDs. The proposed model is based on the physical roots of the device operation and on the stability of some device parameters in the current and temperature range of use. Such parameters are the ideality factor of the Shockley equation in the electric domain and a proposed radiant voltage parameter in the optical domain. This latter accurately describes the radiant flux decay at high current levels.The modelling of the thermal domain is based on the structure function approach. A common instrumentation in a combined measurement can serve the automated generation of all model parameters in the future.