Origin of diameter-dependent growth direction of silicon nanowires.
A nucleation thermodynamic model was developed to clarify the diameter-dependent crystallographic orientation of silicon nanowires (SiNWs) grown via the vapor-liquid-solid (VLS) mechanism with an Au catalyst. The calculated critical energies (E(r*)) and corresponding critical radii (r*) of the SiNWs with <111> and <110> orientations as a function of Au-catalyst size (D(Au)) revealed that the 110-oriented SiNW with r is preferred below D(Au) = approximately 25 nm, but the preferred direction changes to <111> above D(Au) = approximately 25 nm. The model indicated that the nucleated SiNW with a radius (r) above r is stable and continues to grow until the diameter becomes equal to D(Au) but that the crystallographic orientation is maintained. Thus, the predicted growth direction of the final SiNW with a size of D(Au) is <110> for D(Au) < approximately 25 nm and <111> for D(Au) > approximately 25 nm, which is in excellent agreement with reported experimental results.
Wang
C X
CX
Frontier Collaborative Research, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Japan. wangcx@lucid.msl.titech.ac.jp
Hirano
Masahiro
M
Hosono
Hideo
H
D002384:Catalysis; D006046:Gold / Q000737:chemistry; D008962:Models, Theoretical; D049329:Nanostructures; D010316:Particle Size; D044367:Phase Transition; D012666:Semiconductors; D012825:Silicon / Q000737:chemistry*; D013816:Thermodynamics
D006046:Gold; D012825:Silicon