Stacking of 2D materials containing a thin layer of hexagonal boron nitride using polycaprolactone

Abstract

To date, even though many transfer methods for 2D materials have been developed, direct transfer of very thin (< 5 nm) hexagonal boron nitride (hBN) and a monolayer of hBN has been elusive. Herein, a novel transfer method for hBN, including monolayer hBN, is introduced that can form various stacks with many 2D materials. Polycaprolactone (PCL) was selected for the method due to its low melting point and softness at room temperature. With PCL, the stacking method was easily controlled, allowing the formation of many stacks with graphene and hBN. When 2D material transfer was attempted using PCL of various molecular weights, higher molecular weight PCL yielded better results. With increasing average molecular weight, the tensile strength, elongation, and adhesion strength of the PCL sample increased. Higher molecular weight and lower molecular weight distribution assisted in the easy and clean transfer of 2D materials.