Free-floating synthetic nanosheets by atomic layer deposition.

Two-dimensional (2D) nanosheets with distinctive properties are often fabricated by exfoliation, hydrothermal synthesis, or vapor-phase reaction. While these approaches are useful to generate nanosheets, we show that free-floating 2D metal oxide flakes with nanometer-scale thickness can also be formed by atomic layer deposition (ALD), where the ALD process allows the thickness and composition to be precisely tuned. In this work, we describe in detail the ALD nanosheet fabrication process and demonstrate how the choice of the sacrificial substrate affects the subsequent ALD processing and the resulting nanosheet thickness and surface structure. In addition, we introduce the fabrication of organic/inorganic bilayer nanosheets with unique potential applications.