Enhanced Thermoelectric Conversion Efficiency of CVD Graphene with Reduced Grain Sizes
| Autor: | Seung Hwan Ko, Hong Goo Kim, Woorim Lee, Gyumin Lim, Sosan Cheon, Phillip Lee, Jin Young Min, Kyung Rok Pyun, Woomin Lee, Kenneth David Kihm |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Materials science
grain sizes General Chemical Engineering Analytical chemistry 02 engineering and technology Chemical vapor deposition 010402 general chemistry 01 natural sciences Article law.invention lcsh:Chemistry Thermal conductivity CVD graphene law Electrical resistivity and conductivity FET 4-point measurements Seebeck coefficient General Materials Science One half electrical conductivity Graphene food and beverages 021001 nanoscience & nanotechnology Grain size 0104 chemical sciences lcsh:QD1-999 electrical_electronic_engineering thermoelectric conversion efficiency Field-effect transistor 0210 nano-technology |
| Zdroj: | Nanomaterials, Vol 8, Iss 7, p 557 (2018) Nanomaterials Volume 8 Issue 7 |
| Popis: | The grain size of CVD (Chemical Vapor Deposition) graphene was controlled by changing the precursor gas flow rates, operation temperature, and chamber pressure. Graphene of average grain sizes of 4.1 µ m, 2.2 µ m, and 0.5 µ m was synthesized in high quality and full coverage. The possibility to tailor the thermoelectric conversion characteristics of graphene has been exhibited by examining the grain size effect on the three elementary thermal and electrical properties of &sigma S, and k. Electrical conductivity (&sigma ) and Seebeck coefficients (S) were measured in a vacuum for supported graphene on SiO2/Si FET (Field Effect Transistor) substrates so that the charge carrier density could be changed by applying a gate voltage (VG). Mobility (µ ) values of 529, 459, and 314 cm2/V· s for holes and 1042, 745, and 490 cm2/V· s for electrons for the three grain sizes of 4.1 µ m, respectively, were obtained from the slopes of the measured &sigma vs. VG graphs. The power factor (PF), the electrical portion of the thermoelectric figure of merit (ZT), decreased by about one half as the grain size was decreased, while the thermal conductivity (k) decreased by one quarter for the same grain decrease. Finally, the resulting ZT increased more than two times when the grain size was reduced from 4.1 µ m to 0.5 µ m. |
| Databáze: | OpenAIRE |
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