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Resistivity measurements of thin films of bismuth : applications for building bolometric detectors Padwick, Christopher Grant
Abstract
The resistivity of thin bismuth films grown on sapphire substrates has been measured as a function of growth rate, thickness, and temperature. Seven different samples were measured. In all cases the resistivity of the films was completely unlike the resistivity of the bulk material, and each sample exhibited a negative temperature coefficient of resistance (TCR). A model is presented which provides a physical interpretation of the shape of the resistivity - temperature curve of thin bismuth films. This model is a new contribution to this field of research, since there appears to be no satisfactory explanation for the anomalous temperature dependence of the resistivity of thin bismuth films published in the literature. The sheet resistance of the films at 4.2K was found to decrease with increasing thickness. Based on the experimental data, a bismuth film of thickness 200Å should have a sheet resistance of 188.5Ω/ at helium temperatures. The resistance of the thinner films was found to increase as a function of time when exposed to the air, and this seems to be consistent with a layer of insulating Bi₂O₃, forming at the surface of the film. The sheet resistance and resistivity of a 5000Å thick coating of vapor deposited aluminum was measured as a function of temperature in the range 300K — 4.2K. The resistivity was found to be greater than that of the bulk material at all temperatures, and the sheet resistance at 80K was equal to R = 0.051Ω.
Item Metadata
Title |
Resistivity measurements of thin films of bismuth : applications for building bolometric detectors
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1997
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Description |
The resistivity of thin bismuth films grown on sapphire substrates has been measured
as a function of growth rate, thickness, and temperature. Seven different samples were
measured. In all cases the resistivity of the films was completely unlike the resistivity
of the bulk material, and each sample exhibited a negative temperature coefficient of
resistance (TCR). A model is presented which provides a physical interpretation of the
shape of the resistivity - temperature curve of thin bismuth films. This model is a new
contribution to this field of research, since there appears to be no satisfactory explanation
for the anomalous temperature dependence of the resistivity of thin bismuth films
published in the literature.
The sheet resistance of the films at 4.2K was found to decrease with increasing thickness.
Based on the experimental data, a bismuth film of thickness 200Å should have a
sheet resistance of 188.5Ω/ at helium temperatures. The resistance of the thinner films
was found to increase as a function of time when exposed to the air, and this seems to
be consistent with a layer of insulating Bi₂O₃, forming at the surface of the film. The
sheet resistance and resistivity of a 5000Å thick coating of vapor deposited aluminum
was measured as a function of temperature in the range 300K — 4.2K. The resistivity
was found to be greater than that of the bulk material at all temperatures, and the sheet
resistance at 80K was equal to R = 0.051Ω.
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Extent |
9144267 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-03-26
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0085088
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1997-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.