Radially resolved electronic structure and charge carrier transport in silicon nanowires

The electronic structure of silicon nanowires is studied using density functional theory. A radially resolved density of states is discussed for different nanowire diameters and crystal orientations, which allows new insight into the transport properties. Strong differences between the surface and the center of the nanowire are found, indicating that the carrier transport will mainly take place in the nanowire center. For increasing diameter the density of states in the center approaches the bulk value. We find that bulk properties such as the indirect nature of the band gap become already significant at a nanowire diameter of approximately 5 nm and beyond. Finally, the spatial characteristic of the current is visualized in terms of transmission pathways. The electron transport is found to be more localized in the nanowire center compared to the hole transport. It also depends on the crystal orientation of the wire.