Freestanding 2D Glasses by Atomic Layer Deposition

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Atomic Layer Deposition (ALD) enables precise synthesis of ultrathin materials.
• Strong substrate-ALD interactions hinder the fabrication of freestanding 2D films.
• Existing methods face challenges in substrate removal without damaging the ultrathin films.

Purpose of the Study:

• To develop a novel strategy for fabricating freestanding, large-area ultrathin films using ALD.
• To overcome the limitations of substrate removal in ALD processes.
• To enable access to freestanding 2D amorphous materials (glasses) at scale.

Main Methods:

• Growing ultrathin films (alumina, titania) on single-crystal sodium chloride (NaCl) substrates.
• Modifying the NaCl surface by inserting hydroxyl groups to create a heterogeneous interface.
• Utilizing a poly(methyl methacrylate) scaffold for transferring the freestanding films to arbitrary substrates.

Main Results:

• Successfully fabricated freestanding, amorphous ultrathin alumina and titania films.
• Demonstrated facile removal of the films from the modified NaCl substrate under mild conditions with minimal damage.
• Achieved large-area films (1 cm²) with low crack and pinhole density, transferable to new substrates.

Conclusions:

• The tailored NaCl substrate strategy effectively facilitates the production of freestanding ultrathin films via ALD.
• This method provides a scalable and accessible route to fabricating 2D amorphous materials.
• The developed technique opens new possibilities for applications requiring large-area, freestanding ultrathin films.