The Method for Measuring the Distribution Profile of the 3-dB Frequencies of Electroluminescence Over the Area of the LED Chip

A method for measuring the distribution profile of the 3-dB frequencies of electroluminescence (EL) over the area of the light-emitting diode (LED) chip is presented. The distribution profile of the 3-dB frequencies of EL is determined by calculating according to the corresponding functional dependence from the results of measurements by a digital CMOS camera of the LED emission distribution profiles when the LED is supplied by low-frequency current pulses of the order of 1 kHz and high-frequency current pulses with the application of reverse polarity voltage at the end of the current pulse. Experimental approbation of the measurement method was carried out on the example of commercial green and blue InGaN LEDs. The reliability is confirmed by comparing the results of measurements of the average value of the 3-dB frequency, obtained by the presented method, with the results of measurements obtained by a standard method using a harmonic test signal. The measurement method can be used to assess the degree of inhomogeneity of the EL parameters of LED chips and to determine the parameters of the heterostructure in local areas.