arXiv subjects

Ferdinand Grueneis

Publications and source records attributed to Ferdinand Grueneis.

6 recordsLinked to original sources

arXiv2025

Intermittent shot noise generating 1/f fluctuations

When the rate of shot noise is controlled by on-off states we speak of intermittent shot noise. The on-off states lead to alternately occurring clusters of events and intermissions, respectively. We derive the power spectrum of the intermittent shot noise by applying the Wiener-Khinchin theorem. Besides reduced shot noise, we obtain excess noise, which depends on the parameters of the on-off states. We calculate the excess noise for power-law distributed on-states; within the scaling region, the excess noise is excellently approximated by C/f^b. The behavior of the slope b and of the amplitude C in dependence of the on-off times is investigated. For large scaling regions we find a preference for a pure 1/f shape. Finally, we regard the variance of events occurring within a time interval. In the presence of 1/f fluctuations, the variance of counts attains extreme values which are accompanied by an extreme property of slope b.

cond-mat.stat-mech↗

arXiv2022

1/f Noise Under Drift And Thermal Agitation In Semiconductor Materials

Voss and Clarke observed 1/f noise in the square of Johnson noise across samples in thermal equilibrium without applying a current. We refer to this phenomenon as thermal 1/f noise. Voss and Clarke suggested spatially correlated temperature fluctuations as an origin of thermal 1/f noise; they also showed that thermal 1/f noise closely matches the 1/f spectrum obtained by passing a current through the sample. An intermittent generation-recombination (g-r) process has recently been introduced to interpret 1/f noise in semiconductors. The square of this intermittent g-r process generates a 1/f noise component which correlates with Voss and Clarke's empirical findings. Traps which intermittently rather than continuously generate g-r pulses are suggested as the origin of 1/f noise under drift and thermal agitation. We see no need to introduce correlated temperature fluctuations or oxide traps with a large distribution of time constants to explain 1/f noise.

cond-mat.stat-mech↗

arXiv2021

An alternative form of Hooge's relation for 1/f noise in semiconductor materials

Single quantum dots and other materials exhibit irregular switching between on and off states; these on-off states follow power-law statistics giving rise to 1/f noise. We transfer this phenomenon (also referred to as on-off intermittency) to the generation and recombination (g-r) process in semiconductor materials. In addition to g-r noise we obtain 1/f noise that can be provided in the form of the Hooge relation. The predicted Hooge coefficient depends on the parameters of the g-r noise and on the parameters of the intermittency. Due to the power-law distribution of the on-times, the coefficient for intermittency shows a smooth dependence on time t. We also suggest an alternative form of the 1/f noise formula by Hooge relating the 1/f noise to the number of centers (such as donor or trap atoms) rather than to the number of charge carriers as defined by Hooge.

physics.gen-ph↗

arXiv2021

Estimation of the lowest limit of 1/f noise in semiconductor materials

A lowest limit of 1/f noise in semiconductor materials has not yet been reported; we do not even know if such a lowest limit exists. 1/f noise in semiconductors has recently been brought into relation with 1/f noise in quantum dots and other materials. These materials exhibit on-off states which are power-law distributed over a wide range of timescales. We transfer such findings to semiconductors, assuming that the g-r process is also controlled by such on-off states. As a result, we obtain 1/f noise which can be expressed in the form of the Hooge relation. Based on the intermittent g-r process, we estimate the lowest limit of 1/f noise in semiconductor materials. We show that this limit is inversely proportional to the dopant concentration; to detect the lowest limit of 1/f noise, the number of centers should be as small as possible. We also find a smooth dependence of 1/f noise and g-r noise on time.

physics.gen-ph↗

arXiv2012

The Quantum Mechanical Oscillator as a Possible Source of 1/f Fluctuations

We investigate consecutive absorption or emission of photons of the quantum mechanical harmonic oscillator as a possible source of 1/f fluctuations. Separating the absorption and emission process, we show that consecutively absorbed or emitted photons give rise to an intermittent stochastic process; thereby fluctuating clusters of photons are intermitted by distinct breaks. Let the number of photons in a cluster be m and the cluster size distribution be pm. We find that the intermittent process with a cluster size distribution pm proportional to m-2 generates a pure 1/f spectrum. We show that 1/f fluctuations are present in thermal equilibrium but average out to zero. As an example we investigate phonons as a possible origin of 1/f fluctuations in an extrinsic semiconductor. Acoustic phonons always produce a change in the volume; this affects the donor ionization energy modulating also the g-r process. We calculate the spectrum of such a modulated g-r process; thereby the intermittent character of phonon activity is identified as the origin of 1/f fluctuations. The Hooge parameter is found to depend on the mean number of phonons comprised in a cluster, on the modulation depth of the g-r process and on a factor which describes the temperature dependence of 1/f noise.

physics.data-an↗

arXiv2012

1/f Noise and the Infrared Catastrophe

It is generally assumed that stochastic processes exhibiting 1/f noise are affected with the so-called infrared catastrophe. We present an intermittent stochastic process generating 1/f noise which avoids this problem.

physics.data-an↗