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Growth and characterization of gold catalyzed SiGe nanowires and alternative metal-catalyzed Si nanowires.

Potié A, Baron T, Dhalluin F, Rosaz G, Salem B, Latu-Romain L, Kogelschatz M, Gentile P, Oehler F, Montès L, Kreisel J, Roussel H - Nanoscale Res Lett (2011)

Bottom Line: Ge concentration (x) in Si1-xGex NW has been successfully varied by modifying the gas flow ratio: R = GeH4/(SiH4 + GeH4).Second, the results of Si NW growths by CVD using alternatives catalysts such as platinum-, palladium- and nickel-silicides are presented.This approach allows the measurement of as-grown single NW's Young modulus and spring constant, and alleviates uncertainties inherent in single point measurement.

View Article: PubMed Central - HTML - PubMed

Affiliation: LTM/CNRS-CEA-LETI, 17, rue des martyrs, 38054 Grenoble, France. alexis.potie@cea.fr.

ABSTRACT
The growth of semiconductor (SC) nanowires (NW) by CVD using Au-catalyzed VLS process has been widely studied over the past few years. Among others SC, it is possible to grow pure Si or SiGe NW thanks to these techniques. Nevertheless, Au could deteriorate the electric properties of SC and the use of other metal catalysts will be mandatory if NW are to be designed for innovating electronic. First, this article's focus will be on SiGe NW's growth using Au catalyst. The authors managed to grow SiGe NW between 350 and 400°C. Ge concentration (x) in Si1-xGex NW has been successfully varied by modifying the gas flow ratio: R = GeH4/(SiH4 + GeH4). Characterization (by Raman spectroscopy and XRD) revealed concentrations varying from 0.2 to 0.46 on NW grown at 375°C, with R varying from 0.05 to 0.15. Second, the results of Si NW growths by CVD using alternatives catalysts such as platinum-, palladium- and nickel-silicides are presented. This study, carried out on a LPCVD furnace, aimed at defining Si NW growth conditions when using such catalysts. Since the growth temperatures investigated are lower than the eutectic temperatures of these Si-metal alloys, VSS growth is expected and observed. Different temperatures and HCl flow rates have been tested with the aim of minimizing 2D growth which induces an important tapering of the NW. Finally, mechanical characterization of single NW has been carried out using an AFM method developed at the LTM. It consists in measuring the deflection of an AFM tip while performing approach-retract curves at various positions along the length of a cantilevered NW. This approach allows the measurement of as-grown single NW's Young modulus and spring constant, and alleviates uncertainties inherent in single point measurement.

No MeSH data available.


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SEM images, Raman spectra and Ge fraction of SiGe NW. SEM images of SiGe NW grown during 40 min at 375°C with (a) R = 0.15 and (b) R = 0.09. (c) Raman spectra collected from samples (a,b). Arrows are pointing at the Si-Si peaks in SiGe used for calculating the Ge fraction. The inset highlights the peaks' shift between two different compositions (Raman shift = 488 cm-1 for R = 0.15 and 499 cm-1 for R = 0.09). (d) Representation of the Ge composition of the SiGe NW as a function of R.
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Figure 2: SEM images, Raman spectra and Ge fraction of SiGe NW. SEM images of SiGe NW grown during 40 min at 375°C with (a) R = 0.15 and (b) R = 0.09. (c) Raman spectra collected from samples (a,b). Arrows are pointing at the Si-Si peaks in SiGe used for calculating the Ge fraction. The inset highlights the peaks' shift between two different compositions (Raman shift = 488 cm-1 for R = 0.15 and 499 cm-1 for R = 0.09). (d) Representation of the Ge composition of the SiGe NW as a function of R.

Mentions: To change the Ge composition of the NW, the gas ratio R is varied at a constant temperature of 375°C. Figure 2 shows NW grown with R = 0.15 and R = 0.09 and their respective Raman spectra. It was observed that the NW diameters vary from 20 to 60 nm, whatever be the growth conditions. The growth speed increases linearly from 15 to 75 nm min-1 when R decreases from 0.15 to 0.048. This increase can be imputed to the increase of the SiH4 partial pressure and thus of the silane deposition rate. DRX and Raman measurements revealed that the Ge concentration (x) of the Si1-xGex NW has been successfully varied from 0.2 to 0.46 with R varying from 0.048 to 0.15, respectively (Figure 2d).


Growth and characterization of gold catalyzed SiGe nanowires and alternative metal-catalyzed Si nanowires.

Potié A, Baron T, Dhalluin F, Rosaz G, Salem B, Latu-Romain L, Kogelschatz M, Gentile P, Oehler F, Montès L, Kreisel J, Roussel H - Nanoscale Res Lett (2011)

SEM images, Raman spectra and Ge fraction of SiGe NW. SEM images of SiGe NW grown during 40 min at 375°C with (a) R = 0.15 and (b) R = 0.09. (c) Raman spectra collected from samples (a,b). Arrows are pointing at the Si-Si peaks in SiGe used for calculating the Ge fraction. The inset highlights the peaks' shift between two different compositions (Raman shift = 488 cm-1 for R = 0.15 and 499 cm-1 for R = 0.09). (d) Representation of the Ge composition of the SiGe NW as a function of R.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211240&req=5

Figure 2: SEM images, Raman spectra and Ge fraction of SiGe NW. SEM images of SiGe NW grown during 40 min at 375°C with (a) R = 0.15 and (b) R = 0.09. (c) Raman spectra collected from samples (a,b). Arrows are pointing at the Si-Si peaks in SiGe used for calculating the Ge fraction. The inset highlights the peaks' shift between two different compositions (Raman shift = 488 cm-1 for R = 0.15 and 499 cm-1 for R = 0.09). (d) Representation of the Ge composition of the SiGe NW as a function of R.
Mentions: To change the Ge composition of the NW, the gas ratio R is varied at a constant temperature of 375°C. Figure 2 shows NW grown with R = 0.15 and R = 0.09 and their respective Raman spectra. It was observed that the NW diameters vary from 20 to 60 nm, whatever be the growth conditions. The growth speed increases linearly from 15 to 75 nm min-1 when R decreases from 0.15 to 0.048. This increase can be imputed to the increase of the SiH4 partial pressure and thus of the silane deposition rate. DRX and Raman measurements revealed that the Ge concentration (x) of the Si1-xGex NW has been successfully varied from 0.2 to 0.46 with R varying from 0.048 to 0.15, respectively (Figure 2d).

Bottom Line: Ge concentration (x) in Si1-xGex NW has been successfully varied by modifying the gas flow ratio: R = GeH4/(SiH4 + GeH4).Second, the results of Si NW growths by CVD using alternatives catalysts such as platinum-, palladium- and nickel-silicides are presented.This approach allows the measurement of as-grown single NW's Young modulus and spring constant, and alleviates uncertainties inherent in single point measurement.

View Article: PubMed Central - HTML - PubMed

Affiliation: LTM/CNRS-CEA-LETI, 17, rue des martyrs, 38054 Grenoble, France. alexis.potie@cea.fr.

ABSTRACT
The growth of semiconductor (SC) nanowires (NW) by CVD using Au-catalyzed VLS process has been widely studied over the past few years. Among others SC, it is possible to grow pure Si or SiGe NW thanks to these techniques. Nevertheless, Au could deteriorate the electric properties of SC and the use of other metal catalysts will be mandatory if NW are to be designed for innovating electronic. First, this article's focus will be on SiGe NW's growth using Au catalyst. The authors managed to grow SiGe NW between 350 and 400°C. Ge concentration (x) in Si1-xGex NW has been successfully varied by modifying the gas flow ratio: R = GeH4/(SiH4 + GeH4). Characterization (by Raman spectroscopy and XRD) revealed concentrations varying from 0.2 to 0.46 on NW grown at 375°C, with R varying from 0.05 to 0.15. Second, the results of Si NW growths by CVD using alternatives catalysts such as platinum-, palladium- and nickel-silicides are presented. This study, carried out on a LPCVD furnace, aimed at defining Si NW growth conditions when using such catalysts. Since the growth temperatures investigated are lower than the eutectic temperatures of these Si-metal alloys, VSS growth is expected and observed. Different temperatures and HCl flow rates have been tested with the aim of minimizing 2D growth which induces an important tapering of the NW. Finally, mechanical characterization of single NW has been carried out using an AFM method developed at the LTM. It consists in measuring the deflection of an AFM tip while performing approach-retract curves at various positions along the length of a cantilevered NW. This approach allows the measurement of as-grown single NW's Young modulus and spring constant, and alleviates uncertainties inherent in single point measurement.

No MeSH data available.


Related in: MedlinePlus