Adatom-induced donor states during the early stages of Schottky-barrier formation: Ga, In, and Pb on Si(113)

We performed angle-resolved ultraviolet and soft-x-ray photoelectron spectroscopy for the early stages of Schottky-barrier formation of Ga, In, and Pb on Si(113) at room temperature. In the coverage region below 0.1 monolayer a band-bending behavior, typical for donor states, is found. The energies of the adatom-induced donor states in the band gap depend on the adatoms. The Schottky barrier reaches its final value at a coverage of about one monolayer. The values are 0.35 eV above the valence-band maximum for In and Ga and 0.425 eV for Pb. Measurements with Xe interlayers were made to verify that these interfaces are not reactive

Band bending in the initial stages of Schottky-barrier formation for gallium on Si(113)

We present angle-resolved ultraviolet and soft-x-ray photoelectron spectroscopy results for the Schottky-barrier formation of Ga on p-type Si(113). For the first 0.08 monolayer of Ga, the band bending increases. For higher coverages, it decreases monotonically until it reaches its final value at about 2 monolayers. This change of band bending is found for a Si surface for the first time and supports a recent model calculation. The final barrier height is 0.32±0.10 eV, in good agreement with the values found for low-index surfaces

Determination of band bending at the Si(113) surface from photovoltage-induced core-level shifts

The Si 2p core levels were measured by photoelectron spectroscopy with use of synchrotron radiation for the clean Si(113) 3×2 surface. The core levels exhibit shifts of several hundred meV during the change of sample temperature from 300 to 20 K. We interpret these shifts as due to a release of band bending by saturation surface photovoltage. Together with core-level spectroscopy, this turns out to be a new, highly accurate method in determining Fermi-level pinning. For the clean Si(113) 3×2 surface the pinning position coincides within 25 meV for n- and p-type doped samples. At 20 K, a strong reduction of the Si 2p linewidth is found for the p-type sample, which is only to a lesser degree due to band flattening. An intrinsic linewidth of the Si 2p core level of 205±30 meV is derived

Structure and electronic properties of the Si(113) surface

The Si(113) surface has been investigated using video low-energy electron diffraction (LEED), angle-resolved UV photoelectron spectroscopy (ARUPS), and high-resolution electron energy-loss spectroscopy (HREELS) of hydrogen adsorption. At 300 K. we find a 3 × 2 reconstruction for the clean Si(113) surface. Hydrogen adsorption proceeds in two steps. During the first step only Si-H bonds are formed, the photoemission from the dangling bonds becomes completely quenched and the 3 × 2 structure is transformed into a 3 × 1-H. These results strongly indicate that the 3 × 2 → 3 × 1-H transformation proceeds without bond breaking and Si transport. In the second step Si-H2 is formed in addition to Si-H and the reconstruction is changed from 3 × 1-H to 1 × 1. We discuss a model for the 3 × 2 structure in which the number of dangling bonds is largely reduced and an easy 3 × 2 → 3 × 1-H transformation is possible. However, a model that meets all experimental demands is still lacking

Gallium Schottky-barrier formation of Si(113)

The Si(113) surface of a p-type sample was studied by AES, LEED and ARUPS using synchrotron light. On the clean surface (3 × 2) and (3 × 1) LEED patterns were found. The (3 × 2) surface is characterized by a strong surface resonance 0.9 eV below EF. The bands are bent downwards by 0.43 eV at room temperature. On this well defined surface the Schottky-barrier formation of Ga was investigated. For the first 0.08 monolayer of Ga the band bending increases. For higher coverages it decreases monotonically until it reaches its final value at about two monolayers. This change of band bending is found for a Si surface for the first time and supports a recent model calculation. The final barrier height is 0.32 ± 0.10 eV, in good agreement with the values found for low-index surfaces