Recently, high efficiency ultraviolet light emitting diodes (LEDs) have been successfully realized using III-nitride material system. Generally, insulating sapphire substrates, used for growth of device epilayer structures, as well as intrinsically high operation voltage make effective thermal management to be one of major factors needed for widespread dissemination of the technology. Thermal management is critical in the design of LED lamps as the temperature affects both output power and reliability of these devices. Most important parameter characterizing thermal management of packaged device is thermal impedance. The thermal impedance determines the increase of the junction temperature of LED over the ambient temperature due to power dissipation. It is a direct indicator of how much heat is generated under certain input power in the p–n junction diode. The junction temperature controls key device parameters such as the emission efficiency and the lifetime.

In this work the junction temperature of deep UV LEDs was determined from measurements of electroluminescence (EL) spectra and forward voltage of these devices. A finite element simulation was performed to get a detailed insight into temperature distribution throughout the device. Good quantitative agreement was achieved between simulated values of the thermal impedance and experimental data obtained via voltage shift or EL peak shift method. Finally, the thermal model of packaged deep UV LED was applied to optimization of the device geometry and packaging solutions to realize deep UV LEDs with low thermal impedance and, therefore, improved performance at high power levels.