Hole-carrier-dominant transport in 2D single-crystal copper

Abstract The intrinsic nature of electronic transport has been screened by the carrier scattering at grain boundaries in two-dimensional noble metals, such as copper. Here, by realizing the impossible assumption of growing without grain boundaries in thin films, we demonstrate that the transport by hole carriers in 2D copper is the intrinsic nature, which has been screened by the scattering of carriers at grain boundaries. Unlike the grain boundaries, twin boundaries are invisible to conduction carriers, but even a slight tilt from regular twin boundaries is recognized as grain boundaries to electrons, so only complete suppression of grain boundaries can reveal the hidden hole-like characteristic of 2D-single crystal copper. The hole carriers can be explained by the concave Fermi surface of the 2D single-crystal copper, which suggests a breakthrough in manipulating the polarity of majority carriers in metals based on grain boundary engineering in a 2D geometry.