High Density of Quantum-Sized Silicon Nanowires with Different Polytypes Grown with Bimetallic Catalysts

ACS Omega. 2021 Sep 29;6(40):26381-26390. doi: 10.1021/acsomega.1c03630. eCollection 2021 Oct 12.

ABSTRACT

When Si nanowires (NWs) have diameters below about 10 nm, their band gap increases as their diameter decreases; moreover, it can be direct if the material adopts the metastable diamond hexagonal structure. To prepare such wires, we have developed an original variant of the vapor-liquid-solid process based on the use of a bimetallic Cu-Sn catalyst in a plasma-enhanced chemical vapor deposition reactor, which allows us to prevent droplets from coalescing and favors the growth of a high density of NWs with a narrow diameter distribution. Controlling the deposited thickness of the catalyst materials at the sub-nanometer level allows us to get dense arrays (up to 6 × 1010 cm-2) of very-small-diameter NWs of 6 nm on average (standard deviation of 1.6 nm) with crystalline cores of about 4 nm. The transmission electron microscopy analysis shows that both 3C and 2H polytypes are present, with the 2H hexagonal diamond structure appearing in 5-13% of the analyzed NWs per sample.

PMID:34660996 | PMC:PMC8515598 | DOI:10.1021/acsomega.1c03630

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