Open AccessHigh Density of Quantum-Sized Silicon Nanowires with Different Polytypes Grown with Bimetallic Catalysts
Author(s) -
Weixi Wang,
E. Ngo,
Ileana Florea,
Martin Foldyna,
Pere Roca i Cabarrocas,
JeanLuc Maurice
Publication year - 2021
Publication title -
acs omega
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.1c03630
Subject(s) - materials science , nanowire , bimetallic strip , chemical vapor deposition , diamond , transmission electron microscopy , metastability , chemical engineering , nanotechnology , silicon , catalysis , optoelectronics , composite material , metallurgy , chemistry , biochemistry , organic chemistry , engineering , metal
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 × 10 10 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.