Valley‐Dependent Transport in Zigzag Silicene Nanoribbons Controlled by Edge Electric Field Coverage Area

By modifying the width ( W ) of the edge electric field coverage area on zigzag silicene nanoribbons (ZSiNRs), the valley‐dependent transport characteristics can be tuned. As W increases, the band bending weakens, the conduction band continues to rise, while the valence band continues to decline, resulting in a decrease in conductance. By applying antisymmetric edge electric fields relative to the central axis, the negative valley polarization ( P KK ’ ) transitions to positive at the Fermi energy ( E F ) determined by the resulting symmetric edge potential ( U AE ), rather than by W . As W increases, the −1 plateau of P KK ’ widens, while the −1/(2 n + 1) plateaus (where n is a positive integer) narrow and eventually vanish within the band bending region. By applying symmetric edge electric fields relative to the central axis, the zero plateau of P KK’ transitions to nonzero plateaus at the Fermi energy, which is not affected by W but by the resulting antisymmetric potential at the top and bottom edges ( U SE ). As W increases, the bandgap, where P KK ’ has no value, widens, while the 0 plateau of P KK ’ narrows until it disappears within the band bending region. When U AE or U SE exceeds a specific threshold value, the impact of W becomes more pronounced. When U AE or U SE becomes sufficiently large and edge electric fields, whether symmetrical or asymmetrical relative to the central axis, are applied to the whole ZSiNR, a wide bandgap will form. The aforementioned results may be applied to the production of various valleytronic devices.