1. Simplified inelastic electron tunneling spectroscopy based on low-noise derivatives.
- Author
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Kesarwani, Shankar, Misra, Shobhna, Saha, Dipankar, Della Rocca, Maria Luisa, Roy, Indrajit, Ganguly, Swaroop, and Mahajan, Ashutosh
- Subjects
TUNNELING spectroscopy ,ELECTRON tunneling ,ELECTRON spectroscopy ,METAL-insulator-semiconductor devices ,TIKHONOV regularization ,CURRENT-voltage characteristics ,FILTERS & filtration - Abstract
A standard experimental setup for Inelastic Electron Tunneling Spectroscopy (IETS) performs the measurement of the second derivative of the current with respect to the voltage ( d 2 I / d V 2 ) using a small AC signal and a lock-in based second harmonic detection. This avoids noise arising from direct differentiation of the current-voltage characteristics (I–V) by standard numerical methods. Here we demonstrate a noise-filtering algorithm based on Tikhonov Regularization to obtain IET spectra (i.e. d 2 I / d V 2 vs. V) from measured DC I–V curves. This leads to a simple and effective numerical method for IETS extraction. We apply the algorithm to I–V data from a molecular junction and a metal-insulator-semiconductor tunneling device, demonstrating that the computed first/second derivatives have a workable match with those obtained from our lock-in measurements; the computed IET spectral peaks also correlate well with reported experimental ones. Finally, we present a scheme for automated tuning of the algorithm parameters well-suited for the use of this numerical protocol in real applications. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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