Large area Al₂O₃-Au raspberry-like nanoclusters from iterative block-copolymer self-assembly

Area of Science:

• Functional nanomaterials
• Surface science
• Nanotechnology

Background:

• Core-satellite nanoclusters offer unique optoelectronic properties.
• Existing synthesis methods are complex and lack surface ordering capabilities.

Purpose of the Study:

• To develop a reproducible and simplified thin film process for fabricating ordered bimetallic raspberry nanoclusters.
• To demonstrate the use of block copolymer (BCP) lithography for controlled nanocluster assembly.

Main Methods:

• Utilized multilayer block copolymer (BCP) nanopatterns for templating.
• Infiltrated BCP nanopatterns with alumina and gold species.
• Employed microscopy and X-ray reflectivity for in-situ analysis.

Main Results:

• Fabricated bimetallic raspberry nanoclusters with alumina cores (~36 nm) and gold satellites (~15 nm).
• Achieved tunable nanodot periodicities (30-80 nm) using BCPs of varying molecular weights.
• Confirmed excellent order and vertical orientation of nanoclusters over wafer-scale areas via grazing-incidence small-angle X-ray scattering.

Conclusions:

• Demonstrated a robust strategy for designing hybrid nanoclusters using BCP infiltration.
• The method allows for the use of various low-cost precursors for diverse nanocluster compositions.
• The controlled nanocluster fabrication is promising for metasurface and optical sensor applications.