Silicon crystallization in nanodot arrays organized by block copolymer lithography
Résumé
Asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers are used to fabricate nanoporous PS templates with different pore diameter depending on the specific substrate neutralization protocol. The resulting polymeric templates are used as masks for the subsequent deposition of a thin (h = 5 nm) amorphous Si layer by electron beam evaporation. After removal of the polymeric film and of the silicon excess, well-defined hexagonally packed amorphous Si nanodots are formed on the substrate. Their average diameter (d < 20 nm), density (1.2 × 1011 cm−2), and lateral distribution closely mimic the original nanoporous template. Upon capping with SiO2 and high temperature annealing (1050 °C, N2), each amorphous Si nanodot rearranges in agglomerates of Si nanocrystals (d < 4 nm). The average diameter and shape of these Si nanocrystals strongly depend on the size of the initial Si nanodot.
Mots clés
Block copolymers
Amorphous films
Nanocrystals
Nanolithography
Nanostructured materials
Self assembly
Silicon oxides
Transmission electron microscopy
Block copolymer lithography
unclassified drug
silicon nanodot
silicon
quantum dot
polystyrene b polymethylmethacrylate block copolymer
Article
crystallization
E beam evaporation
Electron beam evaporation
High-temperature annealing
Lateral distributions
Nanoporous templates
Si nanocrystal
Specific substrates
Amorphous silicon
copolymer
evaporation
film
high temperature
density
synthesis
electron beam