Low‐ and High‐Frequency Noise in LEDs

Light‐emitting diode (LED) degradation is usually associated with defects in the active region. Whereby the noise analysis can be a strong instrument to reveal them. The results of optical noise measurements for commercially available blue LED samples in a wide frequency range from kHz to MHz are reported. Noise spectra are decomposed into components according to the presented theoretical model which includes 1/ f ‐type noise, generation‐recombination noise, and white noise. The 1/ f γ ‐type noise is modeled as a superposition of generation‐recombination noise components at defects with a continuous wide distribution of relaxation lifetimes. The coincidence of the experimental results with 1/ f γ model for the low‐frequency range is proved and a fitting is made. Three noise components that are highly current‐dependent are identified. The corresponding model of temperature dependence for the low‐frequency range is developed. At low currents, the model partially matches the experimental results in the temperature range from 100 to 300 K at low frequencies. However, high‐frequency measurements show deviations from the expected Lorentzian behavior.