Gentle transfer method for water- and acid/alkali-sensitive 2D materials for (S)TEM study

Abstract

We report a method in making transmission electron microscopy sample for both CVD-grown and exfoliated 2D materials without etching process, thus gentle to those 2D materials that are sensitive to water and reactive etchants. Large-scale WS2 monolayer grown on glass, NbS2 atomic layers grown on exfoliated h-BN flakes, and water-sensitive exfoliated TiS2 flakes are given as representative examples. We show that the as-transferred samples not only retain excellent structural integrity down to atomic scale but also have little oxidations, presumably due to the minimum contact with water/etchants. This method paves the way for atomic scale structural and chemical investigations in sensitive 2D materials.