Kitchen cling film enables reliable transfer of large 2D-material layers onto patterned surfaces

Two-dimensional (2D) materials such as graphene and transition-metal dichalcogenides (TMDCs) offer electrical, mechanical and optical properties useful for electronics and photonics. Producing large-area sheets and transferring them intact onto other substrates has been a persistent bottleneck, especially when the target surfaces are patterned, have low adhesion, or include high-aspect-ratio features.

Researchers at the University of Amsterdam (UvA) and collaborating institutes adapted an inexpensive polymer—low-density polyethylene (LDPE), commonly known as kitchen cling film—into a stamping tool for transferring large 2D layers. They used gold-assisted exfoliation to produce large-area monolayers (the team cites tungsten disulfide, WS2, as an example) on silica (SiO2) substrates and then transferred those layers to other SiO2 targets, including patterned surfaces.

• A heat-resistant half-sphere stamp is wrapped in LDPE cling film and mounted on an xyz micron-precision stage.
• The target 2D layer is heated to 70 °C.
• The stage advances at 0.5 µm/s until the LDPE contacts the 2D layer.
• Force sensors in the stage measure in-plane (Fx, Fy) and perpendicular (Fz) forces during contact and pickup.

LDPE has a low melting temperature and compliant mechanical properties that allow good conformal contact with a 2D layer and patterned features. The polymer's compliance reduces the chance of cracking or tearing large, thin sheets during pickup and placement. The use of a heat-resistant holder enables controlled temperature at the interface to aid adhesion and release.

Jorik van de Groep, leader of the 2D Nanophotonics group at UvA-Institute of Physics, states that the method "allows us, for the first time, to pick up, transfer and place large (roughly 1-mm-sized) 2D layers on almost arbitrarily patterned surfaces." The team reports near-unity yield, meaning transfers are no longer probabilistic as many earlier methods were.

Instrumented force sensing during stamping provides quantitative control over contact and friction. That control improves repeatability and gives operators feedback to adjust approach speed, temperature or pressure in real time.

Implications for device fabrication

For nanophotonics and other device fields, integrating large-area 2D materials onto substrates that already contain electrical contacts, optical coatings or patterned structures is a practical necessity. This LDPE-stamp approach targets that integration problem: it can handle flat and patterned targets, including high-aspect-ratio and low-adhesion interfaces, which are difficult for traditional transfer methods.

The team applied the method to gold-assisted-exfoliated TMDC monolayers and to hexagonal boron nitride (hBN)/monolayer heterostructures. The demonstration used WS2 as an example of a TMDC monolayer transferred between SiO2 substrates.

A simple, low-cost polymer—kitchen cling film—used as a conformal stamp together with precise motion control and force sensing enables reliable, high-yield transfer of large 2D-material sheets onto patterned and otherwise challenging target surfaces. The approach directly addresses a practical fabrication problem for integrating 2D materials into devices.