Liu, Siyang
(2017)
Electrically-triggered Atomic Emission Spectroscopy on Graphene/oxide/silicon Structure.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
We present a device technology that promises chip-scale atomic emission spectroscopy operating in air ambient at room temperature with low voltage pulses. Analytes are placed on top of a graphene/SiO2/Si (GOS) substrate and are atomized for atomic luminescence under electrical excitation. Here the graphene is designed to serve as an electron-transparent conducting electrode. When applying proper voltage pulses, the thin insulating layer (10-nm thermal grown SiO2) breaks down inducing high local leakage current flow. Injection of kinetic electrons induces explosions, atomizing all the material nearby as well. This explosive fragmentation produces atoms in various excited states. The excited atoms then relax producing characteristic luminescence.
We have investigated the mechanisms of oxide breakdown in a GOS capacitor structure under high-field pulsed voltage drive. Four different configurations are analyzed and compared in terms of bias polarity and substrate conductivity type: inversion or accumulation bias on a GOS structure formed on n-Si or p-Si substrate. Electric field distributions in the GOS structure are analyzed under strong bias near the breakdown field regime, and the resulting quantum yield of electron impact ionization is calculated for SiO2 and Si regions. Oxide breakdown is found to occur more readily in inversion bias than in accumulation bias due to the existence of depletion region. In the case of n-Si GOS under inversion bias, a cascade of impact ionization occur, first in SiO2 and then in Si, resulting in explosive melting of Si in the depletion region. In the p-Si GOS case, impact ionization occurs mostly in SiO2 and near SiO2/Si interface.
Post-AES study reveals significantly different breakdown damages caused by lateral propagation of oxide breakdown in GOS device under inversion high-field: highly localized, circular, protruding/deep melt explosion of Si for the n-Si GOS case; shallow, irregular, widely spread, meandering eruptions in SiO2/Si for the p-Si GOS case. These very different damage morphologies are explained by the different carrier-multiplication processes: a cascade of electron impact ionization, escalating towards the Si depletion region for the n-Si case; carrier multiplication accumulating at the graphene side for the p-Si case.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
14 June 2017 |
| Date Type: |
Publication |
| Defense Date: |
24 March 2017 |
| Approval Date: |
14 June 2017 |
| Submission Date: |
10 March 2017 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
154 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Electrical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Atomic emission; Atomic explosion; Graphene; Graphene/oxide/silicon; breakdown propagation; Impact ionization; |
| Date Deposited: |
14 Jun 2017 18:01 |
| Last Modified: |
14 Jun 2019 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/30948 |
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