Limits...
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

SEM images of PtSi-catalyzed Si NW grown for 30 min at various temperatures: (a) 500°C, (b) 700°C, (c) 800°C. PSiH4 is held constant at 60 mTorr. The NW grown at 700 and 800°C show a tapered shape, whereas the diameter of the NW grown at 500°C is constant (45 nm).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211240&req=5

Figure 3: SEM images of PtSi-catalyzed Si NW grown for 30 min at various temperatures: (a) 500°C, (b) 700°C, (c) 800°C. PSiH4 is held constant at 60 mTorr. The NW grown at 700 and 800°C show a tapered shape, whereas the diameter of the NW grown at 500°C is constant (45 nm).

Mentions: After island's formation, SiH4 in H2 is introduced into the deposition chamber and the growth is studied as a function of the temperature. As one can see in Figure 3, the NW grown at low temperature have a constant diameter along their length whereas growth at higher temperatures results in highly tapered NW. This effect could be explained by uncatalyzed growth on the sidewalls of the NW. The vertical growth rate was estimated at 190 nm min-1, and the lateral growth rate at 6 nm min-1 (T = 700°C; silane partial pressure PSiH4 = 60 mTorr). Another explanation would be the incorporation of the catalyst into the NW resulting in a diminution of its diameter during growth. This phenomenon might not be predominant because the diameter of the NW tip is the same as the initial catalyst island (45 nm).


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 of PtSi-catalyzed Si NW grown for 30 min at various temperatures: (a) 500°C, (b) 700°C, (c) 800°C. PSiH4 is held constant at 60 mTorr. The NW grown at 700 and 800°C show a tapered shape, whereas the diameter of the NW grown at 500°C is constant (45 nm).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: SEM images of PtSi-catalyzed Si NW grown for 30 min at various temperatures: (a) 500°C, (b) 700°C, (c) 800°C. PSiH4 is held constant at 60 mTorr. The NW grown at 700 and 800°C show a tapered shape, whereas the diameter of the NW grown at 500°C is constant (45 nm).
Mentions: After island's formation, SiH4 in H2 is introduced into the deposition chamber and the growth is studied as a function of the temperature. As one can see in Figure 3, the NW grown at low temperature have a constant diameter along their length whereas growth at higher temperatures results in highly tapered NW. This effect could be explained by uncatalyzed growth on the sidewalls of the NW. The vertical growth rate was estimated at 190 nm min-1, and the lateral growth rate at 6 nm min-1 (T = 700°C; silane partial pressure PSiH4 = 60 mTorr). Another explanation would be the incorporation of the catalyst into the NW resulting in a diminution of its diameter during growth. This phenomenon might not be predominant because the diameter of the NW tip is the same as the initial catalyst island (45 nm).

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