LED Internal Quantum Efficiency Meter

A structural schematic and operating principle of the internal quantum efficiency meter of InGaN LEDs are presented. The operation of the device is based on the method of measuring the internal quantum efficiency, which consists in measuring the emission power and the 3 dB frequency of the LED electroluminescence at two currents in the range from 10 μA to 100 μA and calculating the value of the internal quantum efficiency according to the given formula. The results of measurements of the internal quantum efficiency of various types of commercial LEDs are presented. It is shown that the distribution of LEDs by the value of the internal quantum efficiency is more uniform than the distribution by the value of the emission power, which is explained by the difference in the light extraction efficiency from the active region of the LEDs of the studied samples.