Deterministic transfer of two-dimensional materials by all-dry viscoelastic stamping

TLDR

Deterministic transfer of two‑dimensional crystals is essential for fabricating heterostructures and integrating them into complex devices, yet existing methods rely on sacrificial polymer layers and wet chemistry. This study aims to develop an all‑dry transfer technique that uses viscoelastic stamps and eliminates any wet chemistry step. The method employs viscoelastic stamps to pick up and place two‑dimensional crystals without exposure to liquids. The dry process removes capillary forces, enabling free suspension of the crystals, and is quick, efficient, clean, and yields high fabrication success.

Abstract

The deterministic transfer of two-dimensional crystals constitutes a crucial step towards the fabrication of heterostructures based on the artificial stacking of two-dimensional materials. Moreover, controlling the positioning of two-dimensional crystals facilitates their integration in complex devices, which enables the exploration of novel applications and the discovery of new phenomena in these materials. To date, deterministic transfer methods rely on the use of sacrificial polymer layers and wet chemistry to some extent. Here, we develop an all-dry transfer method that relies on viscoelastic stamps and does not employ any wet chemistry step. This is found to be very advantageous to freely suspend these materials as there are no capillary forces involved in the process. Moreover, the whole fabrication process is quick, efficient, clean and it can be performed with high yield.