2024-03-28T21:42:58Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1813622022-12-15T08:23:00Zcom_10261_36com_10261_4col_10261_289
Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering
Pérez Taborda, Jaime Andrés
Romero Fanego, Juan José
Abad Mayor, Begoña
Muñoz Rojo, Miguel
Mello, A.
Briones Fernández-Pola, Fernando
Martín-González, Marisol
European Commission
Ministerio de Economía y Competitividad (España)
Banco Santander
Centro Brasileiro de Pesquisas Físicas (Brasil)
Thermal conductivity
Thermoelectric materials
Silicon germanium
Sputtering
SixGe1−x alloys are well-known thermoelectric materials with a high figure of merit at high
temperatures. In this work, metal-induced crystallization (MIC) has been used to grow Si0.8Ge0.2
films that present improved thermoelectric performance (zT = 5.6 × 10−4 at room temperature)
—according to previously reported values on films—with a relatively large power factor
(σ · S2 = 16 μW · m−1 · K−2
). More importantly, a reduction in the thermal conductivity
at room temperature (κ = 1.13 ± 0.12 W · m−1 · K−1
) compared to other Si–Ge films
(∼3 W · m−1 · K−1
) has been found. Whereas the usual crystallization of amorphous SiGe
(a-SiGe) is achieved at high temperatures and for long times, which triggers dopant loss, MIC
reduces the crystallization temperature and the heating time. The associated dopant loss is thus
avoided, resulting in a nanostructuration of the film. Using this method, we obtained Si0.8Ge0.2
films (grown by DC plasma sputtering) with appropriate compositional and structural properties.
Different thermal treatments were tested in situ (by heating the sample inside the deposition
chamber) and ex situ (annealed in an external furnace with controlled conditions). From the
studies of the films by: x-ray diffraction (XRD), synchrotron radiation grazing incidence x-ray
diffraction (SR-GIXRD), micro Raman, scanning electron microscopy (SEM), x-ray
photoemission spectroscopy (XPS), Hall effect, Seebeck coefficient, electrical and thermal
conductivity measurements, we observed that the in situ films at 500 °C presented the best zT
values with no gold contamination.
This work has been supported by the 7th framework of the European project NANOHITEC 263306, the national project PHOMENTA MAT2011-27911, and Infante 201550E072. J A Pérez Taborda acknowledges the Spanish Ministerio de Economia y Competitividad for their FPI grant, and Banco Santander for their special grant for a short stay in Brazil (Brazilian Center of Physical Researches, Rio de Janeiro). Special thanks go to Marta Rull for her assistance in the treatment of the ex situ samples and I Fernández-Martínez of Nano4Energy for his assistance in the commissioning of the sputtering system. The authors wish to thank the Synchrotron Light Brazilian National Laboratory (LNLS)—XRD2 beam line—in Campinas, Brazil, for the XRD measurements (Dr Elvis Lopez and Dr R Ospina, Lab. of Surface and Nanostructures, Centro Brasileiro de Pesquisas Físicas-RJ, Brazil).
Peer reviewed
2019-05-14T08:46:42Z
2019-05-14T08:46:42Z
2016-03-11
artículo
http://purl.org/coar/resource_type/c_6501
Nanotechnology 27(17): 175401 (2016)
0957-4484
http://hdl.handle.net/10261/181362
10.1088/0957-4484/27/17/175401
1361-6528
http://dx.doi.org/10.13039/100010784
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100003545
http://dx.doi.org/10.13039/501100003329
en
#PLACEHOLDER_PARENT_METADATA_VALUE#
info:eu-repo/grantAgreement/EC/FP7/263306
http://dx.doi.org/10.1088/0957-4484/27/17/175401
Sí
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