Electronic structure of Si(110)-(16 x 2) studied by scanning tunneling spectroscopy and density functional theory

The electronic structure of the Si(110)-(16 x 2) surface was studied by scanning tunneling microscopy at room temperature (RT) and at 78 K. A combination of point tunneling spectroscopy measurements and local density of states mappings reveal details of the electronic structure of the (16 x 2) reconstruction both in empty and occupied states. Point tunneling spectra show a small band gap indicating that Si(110)-(16 x 2) is a semiconductor. The pentagon, which is the main building block in the Si(110)-(16 x 2) surface, consists of at least four electronic states. The pentagon in empty states is created by the superposition of two states with different origins: a four-lobed pattern similar to that observed in filled states; and another state that causes splitting of one of the lobes. The 78 K data show that the band responsible for the four-lobed shape in filled states (located at -0.2 eV) splits further. We present a very simple structure, calculated by density functional theory, which partially explains the experimental data.