Hydrogen concentration and temperature affect the 1/f resistance noise in Nb films
Nevins, Bryan Dexter
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https://hdl.handle.net/2142/18888
Description
Title
Hydrogen concentration and temperature affect the 1/f resistance noise in Nb films
Author(s)
Nevins, Bryan Dexter
Issue Date
1991
Doctoral Committee Chair(s)
Weissman, Michael B.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
hydrogen
hydrogen concentration
1/f resistance
1/f resistance fluctuations
thin flims
thing Nb films
resistance noise
Gorsky effect
Snoek effect
Language
en
Abstract
"The 1 /f resistance fluctuations of thin Nb films was studied from
60 K to 400 K. The resistance noise came from hydrogen ions and other
defects placed in the films during sputtering. Hydrogen ions cause three
types of 1/f noise at different temperatures. The noise is related to
internal friction phenomena such as the Gorsky effect and the Snoek
effect. Near 150K, there is ""hopping noise"" caused by the movement of
hydrogen ions between nearby lattice locations. Near 300K, there is
""number fluctuation noise"" due to ions diffusing in and out of the sample
during a noise measurement. The number of ions within the sample
fluctuates, changing the amount of electron scattering and the
resistance. Both hopping noise and number fluctuations are eliminated if
an electric field drains H ions out of the sample. The intensity and
temperature dependence of the hopping noise and the number fluctuation
noise were compared for five samples. This comparison gives
information about hydrogen ion motion and film quality. At frequencies
above the number fluctuation noise, there was 1/f noise with a less
specific origin. This noise is reduced, but not eliminated by the
application of a DC electric field. This noise showed non-Gaussian
effects in some samples. The non-Gaussian noise and other effects
suggest that the noise involves a complex interaction between the H ions
and the Nb lattice in which the motion of ions is correlated over 1 Onm."
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