Metal-Semiconductor Nanocontacts: Silicon Nanowires

Silicon nanowires assembled from clusters or etched from the bulk, connected to aluminum electrodes and passivated, are studied with large-scale local-density-functional simulations. Short $\left(\sim 0.6\mathrm{nm}\right)$ wires are fully metallized by metal-induced gap states resulting in finite conductance $(\sim e^2/h)$. For longer wires $\left(\sim 2.5\mathrm{nm}\right)$ nanoscale Schottky barriers develop with heights larger than the corresponding bulk value by $40\%$ to $90\%$. Electric transport requires doping dependent gate voltages with the conductance spectra exhibiting interference resonances due to scattering of ballistic channels by the contacts.