Large-Area Aligned and Long SiNWs via Flow Control

Large-Area Aligned and Long SiNWs via Flow Control [62] 

Until now we have discussed the effect of two parameters on the SiNW growth temperature and carrier gas. Now we show that the carrier gas flow can be exploited as well. In this particular example we use it to grow millimeter-area arrays of highly oriented, crystalline silicon nanowires of millimeter length. 

The growth in this particular case was performed by thermal evaporation of SiO powder. A carrier gas of argon mixed with 5% H2 was used with a flow of 50 seem at 400 Torn The furnace temperature was 1300 °C, while the growth temperature was about 930 °C. 

HRTEM shows the typical SiNW Si core encapsulated by a Si02 sheath and the 111 planes of crystalline silicon. The diameters of the crystalline silicon core varied from 13 to 30 nm, and the mean value was about 20 nm. The thickness of the amorphous silicon oxide shell varied from 2 to 10 nm, and the mean value was about 5 nm. 

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