The effect of pattern density and wire diameter on the growth rate of micron diameter silicon wires

Silicon microwires (SiMWs) were grown by the vapor–liquid–solid process using gold thin films and gold patterned Si substrates. By precisely controlling the volume of gold within each pore, one wire of the desired wire diameter can be grown from each pore for wires with diameters up to 3 μm. The growth rate was found to decrease with increasing wire density for a constant wire diameter. Additionally, the micron diameter wires exhibited a decreasing growth rate with increasing wire diameter. This was further confirmed by experiments carried out using a gold thin film, where the diameter-dependent growth rate was observed to change from increasing with wire diameter in the small wire diameter range to a reduction in the growth rate for wire diameters greater than 1.25 μm. The decrease in growth rate with diameter for large diameter wires was determined to arise from the time required for the Au–Si droplet to supersaturate once exposed to the SiCl4 precursor, as confirmed by growths with durations shorter than the nucleation time.

► Patterned growth of silicon micron diameter wires using CVD and the VLS growth mechanism.
► Wire diameter directly relates to the gold volume deposited in the pores.
► Increasing pattern density reduces the wire growth rate for a constant wire diameter.
► Wire growth rate increased and then decreased once the diameter exceed ∼2° μμm.
► Reduction in growth rate associated to a nucleation time and confirmed with short growths.