The electronic structure and the metallization onset of single-domain K/Si(100)2×1 have been investigated with angle-resolved polarization-sensitive ultraviolet photoemission. The electronic states producing the surface metallization have been studied for increasing K coverages up to room-temperature saturation. As K coverage increases, the interface undergoes a transition at a critical coverage, from a low-coverage semiconducting phase, to a saturation-coverage metallic phase. Two different surface states (${\mathit{F}}_1$ and ${\mathit{F}}_2$) have been detected in the vicinity of the Fermi level. These two states are sequentially filled along the metallization process. The coverage dependence of both ${\mathit{F}}_1$ and ${\mathit{F}}_2$, and their symmetry properties indicate that the metallization is due to the filling of an initially empty surface band (appearance of ${\mathit{F}}_2$). We relate ${\mathit{F}}_1$ to the completion of K chains in the single-domain surface. The changes detected in K 3p line shape correlate well with the modifications of the valence band, and support that the surface remains semiconducting up to the filling of ${\mathit{F}}_2$. © 1996 The American Physical Society.

• Received 12 July 1996

DOI:https://doi.org/10.1103/PhysRevB.54.R14277