Low-frequency noise of near UV LEDs

Low-frequency noise characteristics of high power near ultraviolet light-emitting diodes (LEDs) with peak radiative wavelengths in a range of 380–410 nm are investigated in a temperature interval of 110–293 K. The defect-assisted tunnelling current component has been observed in some 380 nm peak wavelength samples with corresponding Lorentzian-type electrical noise spectra. Other samples (with a peak wavelength of 390–410 nm) have mainly 1/fα-type electrical fluctuations. Cross-correlation coefficient analysis between electrical and optical fluctuations has been performed in order to evaluate whether the observed defect levels, responsible for additional generation–recombination (g–r) noise components in LEDs noise spectra, are related to the active layer or to the peripheral area of the device. Activation energies of these g–r centres have been also evaluated using g–r noise spectroscopy.