Thermoelectric models of high-power bipolar semiconductor devices. Part II. Nonlinear model of LEDs

A thermoelectric model of a high-power heterojunction LED is developed, and the distributions of temperature and current density in the LED structure are obtained with allowance for several effects of thermal feedback. It is demonstrated that the dependence of the quantum efficiency on the current density and temperature leads to a significant nonuniformity of the temperature and current-density distributions in the LED structure. The calculated results are proven by the experimental dependences of the junction-housing thermal resistances of particular LEDs on the current. The Comsol Multiphysics simulation medium is interactively involved in the calculation and analysis of the temperature and current-density distributions in the LED structure with a thermophysical macrodefect in the approximation of the local thermal feedback. A critical size of the macrodefect that corresponds to the maximum nonuniformity of the thermal distribution is obtained.