"A Theoretical Analysis of Inelastic Electron Tunneling Spectroscopy (I" by Suravi Karmacharya

Document Type

Thesis - University Access Only

Award Date

2009

Degree Name

Master of Science (MS)

Department / School

Electrical Engineering and Computer Science

Abstract

Gas sensors based on IETS are promising candidates for developing highly sensitive and selective gas sensors. However, the effect of measurement temperature on relative peak positions and heights of IETS spectra was unknown since data analysis technique has not been developed for IET spectra. The objective of this thesis was to theoretically determine the feasibility of gas detection and identification based on IETS by developing an effective spectral analysis technique for room temperature IET data. It was found that IETS was probably not an olfaction mechanism. An analytical method was also developed to optimize IETS tunnel junction fabrication processes for high yield and improved reliability using 1-V response. Simmons theory fit can find the optimum IET barrier parameters for a given tunnel junction which can be related to the junction lifetime. IR spectra and 4K IETS spectra were adjusted for temperature (broadened) using peak broadening equation to create a database of IR and IETS spectra. The effect of temperature broadening on spectral matching was found by determining the correlation index of IR and IETS spectra for 11 gases. Neural network analysis of three IET spectra was also done to determine the feasibility of using it as an IETS data processing technique. Neural network and spectral correlation analysis of room temperature IET spectra suggests that IETS gas identification was feasible at room temperature. Correlation analysis appears to be a better technique as it allowed a larger range of inputs. Future work should include further analysis of neural networks on other spectra and expanding the IETS room temperature database by broadening available IETS 4 K spectra to allow a broader analysis of techniques for gas identification using IETS.

Library of Congress Subject Headings

Gas detectors
Tunneling spectroscopy
Electron spectroscopy

Format

application/pdf

Number of Pages

139

Publisher

South Dakota State University

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