Effect of Nanographene Coating on the Seebeck Coefficient of Mesoporous Silicon

Abstract

Nanographene–mesoporous silicon (G-PSi) composites have recently emerged as a promising class of nanomaterials with tuneable physical properties. In this study, we investigated the impact of nanographene coating on the Seebeck coefficient of mesoporous silicon (PSi) obtained by varying two parameters: porosity and thickness. To achieve this, an electrochemical etching process on p + doped Si is presented for the control of the parameters (thicknesses varying from 20 to 160 µm, and a porosity close to 50%), and for nanographene incorporation through chemical vapor deposition. Raman and XPS spectroscopies confirmed the presence of nanographene on PSi. Using a homemade ZT meter, the Seebeck coefficient of the p + doped Si matrix was evaluated at close to 100 ± 15 µV/K and confirmed by UPS spectroscopy analysis. Our findings suggest that the Seebeck coefficient of the porous Si can be measured independently from that of the substrate by fitting measurements on samples with a different thickness of the porous layer. The value of the Seebeck coefficient for the porous Si is of the order of 750 ± 40 µV/K. Furthermore, the incorporation of nanographene induced a drastic decrease to approximately 120 ± 15 µV/K, a value similar to that of its silicon substrate.

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“…Room-temperature Hall Effects were measured through four-probe measurements (ECOPIA-HMS5500, Republic of Korea). Temperature-dependent Seebeck coefficient (S) variation was systematically observed by using the Peltier module for temperature change monitoring, connected with a Keithley DMM6500, USA (homemade setup as in a previous study [18]). The measurement of the Seebeck coefficient was conducted in the temperature range from 300 K to 360 K. All the characterizations were performed at the GREMI laboratory, Orleans.…”

“…monitoring, connected with a Keithley DMM6500, USA (homemade setup as in a previous study [18]). The measurement of the Seebeck coefficient was conducted in the temperature range from 300 K to 360 K. All the characterizations were performed at the GREMI laboratory, Orleans.…”