Self-organized metal nanostructures through laser-interference driven thermocapillary convection

• Published in: Applied physics letters Vol. 91; no. 4; pp. 043105 - 043105-3
• Main Authors: Favazza, C., Trice, J., Kalyanaraman, R., Sureshkumar, R.
• Format: Journal Article
• Language: English
• Published: United States American Institute of Physics 23-07-2007
• Subjects: CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COBALT; CONVECTION; INTERFERENCE; LASER RADIATION; LASERS; PARTICLES; QUANTUM WIRES; SILICON OXIDES; THIN FILMS
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.2762294

Here the authors investigate self-organization and the ensuing length scales when Co films (
1
-
8
nm
thick) on
Si
O
2
surfaces are repeatedly and rapidly melted by nonuniform (interference) laser irradiation. Pattern evolution produces periodic nanowires, which eventually breakup into nanoparticles exhibiting spatial order in the nearest-neighbor (NN) spacing
λ
NN
2
. For films of thickness
h
0
>
2
nm
,
λ
NN
2
∝
h
0
1
∕
2
while the particle radius varies as
r
p
2
∝
h
0
1
∕
2
. This scaling behavior is consistent with pattern formation by a thermocapillary flow and a Rayleigh-like instability. For
h
0
⩽
2
nm
, a hydrodynamic instability of a spinodally unstable film leads to the formation of nanoparticles.