Point process model of 1/f noise versus a sum of Lorentzians

We present a simple point process model of $1/f^{\beta}$ noise, covering different values of the exponent $\beta$. The signal of the model consists of pulses or events. The interpulse, interevent, interarrival, recurrence or waiting times of the signal are described by the general Langevin equation with the multiplicative noise and stochastically diffuse in some interval resulting in the power-law distribution. Our model is free from the requirement of a wide distribution of relaxation times and from the power-law forms of the pulses. It contains only one relaxation rate and yields $1/f^ {\beta}$ spectra in a wide range of frequency. We obtain explicit expressions for the power spectra and present numerical illustrations of the model. Further we analyze the relation of the point process model of $1/f$ noise with the Bernamont-Surdin-McWhorter model, representing the signals as a sum of the uncorrelated components. We show that the point process model is complementary to the model based on the sum of signals with a wide-range distribution of the relaxation times. In contrast to the Gaussian distribution of the signal intensity of the sum of the uncorrelated components, the point process exhibits asymptotically a power-law distribution of the signal intensity. The developed multiplicative point process model of $1/f^{\beta}$ noise may be used for modeling and analysis of stochastic processes in different systems with the power-law distribution of the intensity of pulsing signals.Comment: 23 pages, 10 figures, to be published in Phys. Rev.

Low-frequency noise properties of beryllium δ-doped GaAs/AlAs quantum wells near the Mott transition

Noise properties of beryllium delta-doped GaAs/AlAs multiple quantum wells, doped both above and below the Mott transition, are studied within the frequency range of 10 Hz-20 kHz and at temperature from 77 K to 350 K. It is shown that the generation-recombination noise in structures close to the Mott transition exhibits two peaks - a frequency and temperature-dependent peak between 120 and 180 K and a broadband, frequency- and temperature- nearly independent peak around 270 K. Activation energies are estimated; origin of the broadband maximum is attributed to holes tunnelling into defect trap states located in the AlAs barrier/GaAs quantum well interface

Optical and Electrical Noise Characteristics of Side Emitting LEDs

Low frequency noise characteristics of nitride based blue side emitting diodes have been investigated. It is shown that investigated devices distinguish by $1//f^α$-type optical and electrical fluctuations caused by various generation-recombination processes through defects formed generation-recombination centers. At higher frequencies optical shot noise due to random photon emission prevails $1//f^α$-type spectrum. The results have shown that low frequency optical and electrical noises are strongly correlated at small current region, but at higher forward current not correlated noise components dominate. Lenses and secondary optics of the investigated devices do not influence output light

Light-Emitting Diode Degradation and Low-Frequency Noise Characteristics

Comprehensive investigation of phosphide-based red and nitride-based blue light-emitting diodes characteristics and physical processes that take place in device structure during aging has been carried out. Analysis of noise characteristics (the emitting-light power and the LED voltage fluctuations, also their cross-correlation factor) shows that investigated LEDs degradation is caused by defects that lead to the leakage current and non-radiating recombination increase in the active region or its interfaces. Appearance of the defects first of all manifests in noise characteristics: intensive and strongly correlated $1//f^{α}$ type optical and electrical fluctuations come out