The following thesis includes a short description of the history, working principle and characteristics of light-emitting diodes. Presented are the problems of elevated temperature of light-emitting diodes, the importance of tracking the temperature and keeping the light-emitting diodes at the recommended temperatures by means of adequate cooling. Described in the thesis are some methods of temperature measurements of the p-n junction, with a detailed description of the EIA/JEDEC JESD51-1 standard, which determines the method for performing temperature measurements of the p-n junction by using two electric currents in forward direction. It is used for temperature measurements of semiconductor devices, including diodes.
In the experimental part of the thesis, performing temperature measurements of the p-n junction of five test light-emitting diodes is presented on the basis of the EIA/JEDEC JESD51-5 standard. The temperature measurements of all five diodes are performed at a room temperature of the environment; additionally, the temperature measurement is performed at elevated temperature of the environment for one diode. The method of temperature measurement of the p-n junction by means of voltage drop is being attested as useful as it gives comparable results with all five measurements at a room temperature, as well as with elevated temperature of the environment. The disadvantage of this method is that it is time-consuming. Light-emitting diodes differ in U-I characteristic and in change of voltage on the p-n junction that is a result of a change of temperature. Therefore, characteristic dependence of the voltage on the temperature (K factor) needs to be measured at every light-emitting diode.