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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.


Related in: MedlinePlus

Young's moduli of GaN NW as a function of the NW radius. The error bar is estimated according to the following formula: ΔE/E = 3/Δa/a/ + 4/Δr/r/. The dashed line represents the GaN bulk modulus in the [0001] direction.
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Figure 9: Young's moduli of GaN NW as a function of the NW radius. The error bar is estimated according to the following formula: ΔE/E = 3/Δa/a/ + 4/Δr/r/. The dashed line represents the GaN bulk modulus in the [0001] direction.

Mentions: Si NW grown along the (111) direction have been tested (results not shown). As expected [32], the measured Young's moduli are comparable to the bulk Si young modulus along the (111) direction. Figure 9 shows the Young modulus of GaN NW with r ranging from 100 to 300 nm determined according to this method. GaN NW grow along the c-axis ([0001] direction) [33], and the doted line on the graph represents the bulk's Young's modulus along the same direction. As one can see, E tends to decrease when the radius increases and becomes much lower than the bulk modulus above r = 150 nm. The same behavior has already been reported for GaN [34] and for ZnO NW [35]. A possible explanation could be a diminution of the defect inside the crystal with the diminution of the diameter. As can be seen in ref [33], the section of GaN NW can be irregular from one NW to another which could explain the wide dispersion of the Young's moduli. Moreover, the NW's cross section becomes more and more irregular, and the crystalline quality decreases as the NW diameter increases [33]. This could explain such a decrease of the GaN NW's Young's moduli when the NW diameters increase. This aspect constitutes the main limit of this method; this is why NW with a regular cylindrical diameter are required to obtain reliable results.


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)

Young's moduli of GaN NW as a function of the NW radius. The error bar is estimated according to the following formula: ΔE/E = 3/Δa/a/ + 4/Δr/r/. The dashed line represents the GaN bulk modulus in the [0001] direction.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 9: Young's moduli of GaN NW as a function of the NW radius. The error bar is estimated according to the following formula: ΔE/E = 3/Δa/a/ + 4/Δr/r/. The dashed line represents the GaN bulk modulus in the [0001] direction.
Mentions: Si NW grown along the (111) direction have been tested (results not shown). As expected [32], the measured Young's moduli are comparable to the bulk Si young modulus along the (111) direction. Figure 9 shows the Young modulus of GaN NW with r ranging from 100 to 300 nm determined according to this method. GaN NW grow along the c-axis ([0001] direction) [33], and the doted line on the graph represents the bulk's Young's modulus along the same direction. As one can see, E tends to decrease when the radius increases and becomes much lower than the bulk modulus above r = 150 nm. The same behavior has already been reported for GaN [34] and for ZnO NW [35]. A possible explanation could be a diminution of the defect inside the crystal with the diminution of the diameter. As can be seen in ref [33], the section of GaN NW can be irregular from one NW to another which could explain the wide dispersion of the Young's moduli. Moreover, the NW's cross section becomes more and more irregular, and the crystalline quality decreases as the NW diameter increases [33]. This could explain such a decrease of the GaN NW's Young's moduli when the NW diameters increase. This aspect constitutes the main limit of this method; this is why NW with a regular cylindrical diameter are required to obtain reliable results.

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