Non-Gaussian Noise Statistics in Undoped Hydrogenated Amorphous Silicon

ABSTRACTMeasurements of coplanar conductance fluctuations in undoped a-Si:H are described. Statistical tests show that the 1/f noise is non-Gaussian and has a power-law frequency dependent second spectrum, as observed in n-type a-Si:H. By careful consideration of the thermal history of the sample, the noise statistics are found to be different above and below the equilibration temperature, which has been associated with hydrogen diffusion. These results suggest that the non-Gaussian noise in a-Si:H is influenced by the motion of bonded hydrogen and is not significantly dependent upon doping.

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Light Induced Changes in the Non-Gaussian Noise Statistics in Doped Hydrogenated Amorphous Silicon

MRS Proceedings ◽

10.1557/proc-297-661 ◽

1993 ◽

Vol 297 ◽

Author(s):

J. Fan ◽

J. Kakalios

Keyword(s):

Amorphous Silicon ◽

Gaussian Noise ◽

Hydrogenated Amorphous Silicon ◽

Noise Power ◽

Defect Creation ◽

Non Gaussian ◽

Noise Statistics ◽

Induced Changes ◽

Many Body Interactions ◽

Hydrogenated Amorphous

The power spectrum of coplanar current fluctuations in n-type doped hydrogenated amorphous silicon (a-Si:H) has been measured before and after metastable defect creation by light soaking. The average magnitude and spectral slope of the 1/f noise are not affected by illumination, however significant changes in the higher order statistics are observed. Associated with the decrease of conductivity upon light soaking (the Staebler-Wronski effect), there is a decrease in the correlation of the noise power which characterize the non-Gaussian noise in the annealed state. These changes in the noise statistics are reversible by annealing. The light-induced changes in the non-Gaussian statistics provide experimental support for models of light induced defect creation which involve long-ranged and many body interactions.

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1/f Noise and Thermal Equilibration Effects in Hot Wire Deposited Amorphous Silicon

MRS Proceedings ◽

10.1557/proc-420-641 ◽

1996 ◽

Vol 420 ◽

Cited By ~ 5

Author(s):

G. M. Khera ◽

J. Kakalios ◽

Q. Wang ◽

E. Iwaniczko

Keyword(s):

Amorphous Silicon ◽

Chemical Vapor ◽

Dark Conductivity ◽

Hot Wire ◽

Thermal Equilibration ◽

Silicon Thin Films ◽

Conductance Fluctuations ◽

Non Gaussian ◽

Noise Statistics ◽

Hydrogenated Amorphous

AbstractMeasurements of the conductance fluctuations and thermal equilibration of the dark conductivity of a series of undoped hydrogenated amorphous silicon thin films synthesized by Hot-Wire Chemical Vapor Deposition (HWCVD), with hydrogen contents varying from less than one to twelve atomic percent are reported. The spectral density of the conductance fluctuations varies inversely with frequency f and is dependent upon hydrogen concentration; the 1/f noise statistics are non- Gaussian, indicating correlated fluctuators as is observed in PECVD a-Si:H. These results indicate that aspects of electronic transport and defect dynamics in HWCVD films are similar to those in PECVD a-Si:H films.

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Light-induced changes of the non-Gaussian 1/f noise statistics in doped hydrogenated amorphous silicon

Philosophical Magazine B ◽

10.1080/01418639408240131 ◽

1994 ◽

Vol 69 (4) ◽

pp. 595-608 ◽

Cited By ~ 35

Author(s):

J. Fan ◽

J. Kakalios

Keyword(s):

Amorphous Silicon ◽

Hydrogenated Amorphous Silicon ◽

Non Gaussian ◽

Noise Statistics ◽

Induced Changes ◽

Hydrogenated Amorphous

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A curvilinear bivariate random changepoint model to assess temporal order of markers

Statistical Methods in Medical Research ◽

10.1177/0962280219898719 ◽

2020 ◽

Vol 29 (9) ◽

pp. 2481-2492

Author(s):

Corentin Segalas ◽

Catherine Helmer ◽

Hélène Jacqmin-Gadda

Keyword(s):

Repeated Measures ◽

Temporal Order ◽

Statistical Tests ◽

Degradation Process ◽

R Package ◽

History Of ◽

Large Heterogeneity ◽

The Times ◽

Non Gaussian ◽

Gaussian Data

In biomedical research, various longitudinal markers measuring different quantities are often collected over time. For example, repeated measures of psychometric scores are very informative about the degradation process toward dementia. These trajectories are generally nonlinear with an acceleration of the decline a few years before the diagnosis and a large heterogeneity between psychometric tests depending on the underlying cognitive function to be evaluated and the metrological properties of the test. Comparing the times of acceleration of the decline before diagnosis between cognitive tests is useful to better understand the natural history of the disease. Our objective is to propose a bivariate random changepoint model that allows for the comparison of the mean time of change between two markers. A frequentist approach is proposed that gives validated statistical tests to assess the temporal order of the changepoints. Using a spline transformation function, the model is designed to handle non-Gaussian data, that are common for cognitive scores which frequently exhibit a strong ceiling effect. The procedure is assessed through a simulation study and applied to a French cohort of elderly to identify the order of the decline of several cognitive scores. The whole methodology has been implemented in a R package freely available.

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NEW INSIGHT INTO THE FLUCTUATIONS OF THE MOVING VORTEX LATTICE: NON-GAUSSIAN NOISE AND LÉVY FLIGHTS

Fluctuation and Noise Letters ◽

10.1142/s0219477506003422 ◽

2006 ◽

Vol 06 (03) ◽

pp. L287-L295 ◽

Cited By ~ 1

Author(s):

J. SCOLA ◽

A. PAUTRAT ◽

C. GOUPIL ◽

CH. SIMON ◽

B. DOMENGÈS ◽

...

Keyword(s):

Gaussian Noise ◽

Vortex Lattice ◽

Vortex Motion ◽

Voltage Noise ◽

Voltage Fluctuations ◽

Flux Flow ◽

Non Gaussian ◽

Noise Statistics ◽

Insight Into ◽

Moving Vortex

We report measurements and analysis of the voltage noise due the to vortex motion, performed in superconducting Niobium micro-bridges. Noise in such small systems exhibits important changes from the behavior commonly reported in macroscopic samples. In the low biasing current regime, the voltage fluctuations are shown to deviate substantially from the Gaussian behavior which is systematically observed at higher currents in the so called flux-flow regime. The responsibility of the spatial inhomogeneities of the critical current in this deviation from Gaussian behavior is emphasized. We also report on the first investigation of the effect of an artificial pinning array on the voltage noise statistics. It is shown that the fluctuations can lose their stationarity, and exhibit a Lévy flight-like behavior.

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Non-Gaussian 1 / f Noise and Conductance Fluctuations in Hydrogenated Amorphous Silicon

MRS Proceedings ◽

10.1557/proc-258-741 ◽

1992 ◽

Vol 258 ◽

Author(s):

C. E. Parman ◽

N. E. Israeloff ◽

J. Kakalios

Keyword(s):

Spectral Analysis ◽

Amorphous Silicon ◽

Hydrogenated Amorphous Silicon ◽

Current Fluctuations ◽

Noise Power ◽

Effective Volume ◽

Conductance Fluctuations ◽

Cooperative Dynamics ◽

Non Gaussian ◽

Hydrogenated Amorphous

ABSTRACTStatistical analysis of the 1/f noise power spectrum of co-planar current fluctuations in n-type doped hydrogenated amorphous silicon (a-Si:H) find that the noise arises from a small number of correlated fluctuators. The noise power displays a complicated time dependence with the noise power changing in both magnitude and as a function of frequency. Spectral analysis of these noise power fluctuations display an approximate 1/f frequency dependence. These results are surprising given the effective volume (∼10-7 cm3) of the sample, and indicate that cooperative dynamics govern conductance fluctuations in a-Si:H.

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