2D and thin-film copper synthesized via magnetron sputtering

Two-dimensional metals have gained great attention in recent years. However, most of these metals possess relatively strong chemical bonding in three directions; therefore, it is difficult to synthesize 2D metals. In this paper, we prepared 2D and thin- film copper materials via magnetron sputtering. 2D and thin-film copper are formed due to the accumulation of strain and stress associated with different coefficients of thermal expansion for the metal and substrate. SEM and AFM studies suggest that the minimum thickness of a freestanding single layer is approximately 1 nm, with lateral dimensions up to a few millimeters.