Strongly adhesive dry transfer technique for van der Waals heterostructure

Abstract

That one can stack van der Waals materials with atomically sharp interfaces has provided a new material platform of constructing heterostructures. The technical challenge of mechanical stacking is picking up the exfoliated atomically thin materials after mechanical exfoliation without chemical and mechanical degradation. Chemically inert hexagonal boron nitride (hBN) has been widely used for encapsulating and picking up vdW materials. However, due to the relatively weak adhesion of hBN, assembling vdW heterostructures based on hBN has been limited. We report a new dry transfer technique. We used two vdW semiconductors (ZnPS 3 and CrPS 4 ) to pick up and encapsulate layers for vdW heterostructures, which otherwise are known to be hard to fabricate. By combining with optimized polycaprolactone (PCL) providing strong adhesion, we demonstrated various vertical heterostructure devices, including quasi-2D superconducting NbSe 2 Josephson junctions with atomically clean interface. The versatility of the PCL-based vdW stacking method provides a new route for assembling complex 2D vdW materials without interfacial degradation.

Ultrahigh Anisotropic Transport Properties of Black Phosphorus Field Effect Transistors Realized by Edge Contact

“…The hBN and BP were picked up in order by using polycaprolactone (PCL) at 42-58 °C. [52] The hBN/BP stack that was picked up by PCL was dropped down at 80 °C on the exfoliated hBN. The polymeric residues remaining after the transfer process were removed in acetone at 70 °C (Figure S1, Supporting Information).…”

The Magnetic Genome of Two-Dimensional van der Waals Materials

“…A pivotal advancement in the 2D materials community was the development of techniques to fabricate vertical heterostructures—stacks consisting of multiple layers of different 2D materials. 408 , 549 , 553 , 804 − 811 Such techniques are especially versatile since they only rely on vdW interactions to produce heterostructures, allowing for nearly infinite possibilities by combining vdW materials with different electronic, magnetic, or physical properties. With the recent discovery of 2D magnetism within the family of available vdW materials, opportunities have arisen for incorporating 2D magnetic layers within more complex heterostructures.…”

Recent Advances on Tuning the Interlayer Coupling and Properties in van der Waals Heterostructures

“…[78] Thereafter, a variety of vdW heterostructures for different applications were realized by mechanical-based transfer methods. [79][80][81][82] During the mechanical transfer and stacking process, a twist angle would be induced between upper and lower layers, causing rotational misalignment which generates symmetry-violating and residual strain. These effects further result in the modulation of interlayer coupling for vdW heterostructure.…”