TU Darmstadt / ULB / TUbiblio

Effect of the Content and Ordering of the sp2 Free Carbon Phase on the Charge Carrier Transport in Polymer-Derived Silicon Oxycarbides

Rosenburg, Felix and Balke, Benjamin and Nicoloso, Norbert and Riedel, Ralf and Ionescu, Emanuel (2020):
Effect of the Content and Ordering of the sp2 Free Carbon Phase on the Charge Carrier Transport in Polymer-Derived Silicon Oxycarbides.
In: Molecules, 25 (24), p. 5919. MDPI, ISSN 1420-3049, e-ISSN 1420-3049,
DOI: 10.3390/molecules25245919,
[Article]

Abstract

The present work elaborates on the correlation between the amount and ordering of the free carbon phase in silicon oxycarbides and their charge carrier transport behavior. Thus, silicon oxycarbides possessing free carbon contents from 0 to ca. 58 vol.% (SiOC/C) were synthesized and exposed to temperatures from 1100 to 1800 degrees C. The prepared samples were extensively analyzed concerning the thermal evolution of the sp(2) carbon phase by means of Raman spectroscopy. Additionally, electrical conductivity and Hall measurements were performed and correlated with the structural information obtained from the Raman spectroscopic investigation. It is shown that the percolation threshold in SiOC/C samples depends on the temperature of their thermal treatment, varying from ca. 20 vol.% in the samples prepared at 1100 degrees C to ca. 6 vol.% for the samples annealed at 1600 degrees C. Moreover, three different conduction regimes are identified in SiOC/C, depending on its sp(2) carbon content: (i) at low carbon contents (i.e., <1 vol.%), the silicon oxycarbide glassy matrix dominates the charge carrier transport, which exhibits an activation energy of ca. 1 eV and occurs within localized states, presumably dangling bonds; (ii) near the percolation threshold, tunneling or hopping of charge carriers between spatially separated sp(2) carbon precipitates appear to be responsible for the electrical conductivity; (iii) whereas above the percolation threshold, the charge carrier transport is only weakly activated (E-a = 0.03 eV) and is realized through the (continuous) carbon phase. Hall measurements on SiOC/C samples above the percolation threshold indicate p-type carriers mainly contributing to conduction. Their density is shown to vary with the sp(2) carbon content in the range from 10(14) to 10(19) cm(-3); whereas their mobility (ca. 3 cm(2)/V) seems to not depend on the sp(2) carbon content.

Item Type: Article
Erschienen: 2020
Creators: Rosenburg, Felix and Balke, Benjamin and Nicoloso, Norbert and Riedel, Ralf and Ionescu, Emanuel
Title: Effect of the Content and Ordering of the sp2 Free Carbon Phase on the Charge Carrier Transport in Polymer-Derived Silicon Oxycarbides
Language: English
Abstract:

The present work elaborates on the correlation between the amount and ordering of the free carbon phase in silicon oxycarbides and their charge carrier transport behavior. Thus, silicon oxycarbides possessing free carbon contents from 0 to ca. 58 vol.% (SiOC/C) were synthesized and exposed to temperatures from 1100 to 1800 degrees C. The prepared samples were extensively analyzed concerning the thermal evolution of the sp(2) carbon phase by means of Raman spectroscopy. Additionally, electrical conductivity and Hall measurements were performed and correlated with the structural information obtained from the Raman spectroscopic investigation. It is shown that the percolation threshold in SiOC/C samples depends on the temperature of their thermal treatment, varying from ca. 20 vol.% in the samples prepared at 1100 degrees C to ca. 6 vol.% for the samples annealed at 1600 degrees C. Moreover, three different conduction regimes are identified in SiOC/C, depending on its sp(2) carbon content: (i) at low carbon contents (i.e., <1 vol.%), the silicon oxycarbide glassy matrix dominates the charge carrier transport, which exhibits an activation energy of ca. 1 eV and occurs within localized states, presumably dangling bonds; (ii) near the percolation threshold, tunneling or hopping of charge carriers between spatially separated sp(2) carbon precipitates appear to be responsible for the electrical conductivity; (iii) whereas above the percolation threshold, the charge carrier transport is only weakly activated (E-a = 0.03 eV) and is realized through the (continuous) carbon phase. Hall measurements on SiOC/C samples above the percolation threshold indicate p-type carriers mainly contributing to conduction. Their density is shown to vary with the sp(2) carbon content in the range from 10(14) to 10(19) cm(-3); whereas their mobility (ca. 3 cm(2)/V) seems to not depend on the sp(2) carbon content.

Journal or Publication Title: Molecules
Journal volume: 25
Number: 24
Publisher: MDPI
Uncontrolled Keywords: silicon oxycarbides; charge carrier transport; free carbon; Raman spectroscopy; Hall measurements TEMPERATURE CREEP-BEHAVIOR; ELECTRICAL-CONDUCTIVITY; LITHIUM STORAGE; SIOC CERAMICS; RAMAN-SPECTROSCOPY; ASPECT-RATIO; GLASSES; NANOCOMPOSITES; RELAXATION; MECHANISM
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
Date Deposited: 18 Jan 2021 06:23
DOI: 10.3390/molecules25245919
Official URL: https://doi.org/10.3390/molecules25245919
Additional Information:

Financial support from the German Science Foundation (DFG, Bonn, Germany, project no. 411658150) is gratefully acknowledged. EI acknowledges furthermore support within the Heisenberg program of the DFG (IO 64/14-1).

Export:
Suche nach Titel in: TUfind oder in Google
Send an inquiry Send an inquiry

Options (only for editors)
Show editorial Details Show editorial Details