Hydrogen concentration and temperature affect the 1/f resistance noise in niobium films
Nevins, Bryan Dexter
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https://hdl.handle.net/2142/19556
Description
Title
Hydrogen concentration and temperature affect the 1/f resistance noise in niobium films
Author(s)
Nevins, Bryan Dexter
Issue Date
1991
Doctoral Committee Chair(s)
Weissman, Michael B.
Department of Study
Physics
Discipline
Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Condensed Matter
Language
eng
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 10nm."
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