Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering

J. A.Perez Taborda, J. J. Romero, B. Abad, M. Muñoz-Rojo, A. Mello, F. Briones, M. S.Martin Gonzalez (Corresponding Author)

Research output: Contribution to journalArticleAcademicpeer-review

15 Citations (Scopus)

Abstract

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.

Original languageEnglish
Article number175401
JournalNanotechnology
Volume27
Issue number17
DOIs
Publication statusPublished - 11 Mar 2016
Externally publishedYes

Fingerprint

Germanium
Nanocrystalline silicon
Sputtering
Thermal conductivity
Crystallization
X rays
Temperature
Diffraction
Metals
Doping (additives)
Heating
Seebeck coefficient
Hall effect
Photoelectron spectroscopy
Synchrotron radiation
Gold
Structural properties
Furnaces
Contamination
Heat treatment

Keywords

  • silicon germanium
  • sputtering
  • thermal conductivity
  • thermoelectric materials

Cite this

Taborda, J. A.Perez ; Romero, J. J. ; Abad, B. ; Muñoz-Rojo, M. ; Mello, A. ; Briones, F. ; Gonzalez, M. S.Martin. / Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering. In: Nanotechnology. 2016 ; Vol. 27, No. 17.
@article{9d4edbf628524ba7a77ec67cb9feaa51,
title = "Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering",
abstract = "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.",
keywords = "silicon germanium, sputtering, thermal conductivity, thermoelectric materials",
author = "Taborda, {J. A.Perez} and Romero, {J. J.} and B. Abad and M. Mu{\~n}oz-Rojo and A. Mello and F. Briones and Gonzalez, {M. S.Martin}",
year = "2016",
month = "3",
day = "11",
doi = "10.1088/0957-4484/27/17/175401",
language = "English",
volume = "27",
journal = "Nanotechnology",
issn = "0957-4484",
publisher = "IOP Publishing Ltd.",
number = "17",

}

Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering. / Taborda, J. A.Perez; Romero, J. J.; Abad, B.; Muñoz-Rojo, M.; Mello, A.; Briones, F.; Gonzalez, M. S.Martin (Corresponding Author).

In: Nanotechnology, Vol. 27, No. 17, 175401, 11.03.2016.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering

AU - Taborda, J. A.Perez

AU - Romero, J. J.

AU - Abad, B.

AU - Muñoz-Rojo, M.

AU - Mello, A.

AU - Briones, F.

AU - Gonzalez, M. S.Martin

PY - 2016/3/11

Y1 - 2016/3/11

N2 - 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.

AB - 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.

KW - silicon germanium

KW - sputtering

KW - thermal conductivity

KW - thermoelectric materials

U2 - 10.1088/0957-4484/27/17/175401

DO - 10.1088/0957-4484/27/17/175401

M3 - Article

VL - 27

JO - Nanotechnology

JF - Nanotechnology

SN - 0957-4484

IS - 17

M1 - 175401

ER -