Electron Waves in theπ*Surface Band of the Si(001) Surface

The unoccupied ${\pi }^{*}$ surface band of the $\mathrm{Si}\left(001\right)-c(4\times 2)$ surface has been determined from standing-wave patterns using low-temperature scanning tunneling microscopy. A straight chain of Al ad-dimers, formed by deposition at room temperature, works as a one-dimensional (1D) barrier that scatters the surface-state electrons. The standing waves have been observed along Si dimer rows in a sample voltage range of 0.9–1.3 V at $T=63\mathrm{}\mathrm{K}$. The relationship between their wavelengths and the sample voltages gives the dispersion relation of the ${\pi }^{*}$ surface band. The height and width of the potential barrier have been estimated according to the 1D Schrödinger equation.