Atomic geometry and electronic structure of the Si(100)2x3-Eu surface phase -: art. no. 085343

The structural and electronic properties of the Eu-induced 2x3 reconstruction on Si(100) have been investigated by scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and high-resolution Si 2p core-level spectroscopy using synchrotron radiation. STM images of this reconstruction are found to be drastically dependent on the bias voltage and tunneling current. STS measurements show that the 2x3-Eu surface is semiconducting. Two occupied states at -0.9 and -1.75 V and three unoccupied states at +0.35, +0.8, and +1.5 V are identified in the (dI/dV)/(I/V) spectrum of this surface. The Si 2p core-level spectra taken at various photon energies and emission angles are revealed to include four surface-related components S1-S4 with core-level shifts of -0.54, -0.24, +0.21, and +0.51 eV, respectively. The S1, S2, and S4 components are assigned to first-layer Si atoms in the 2x3-Eu structure and the S3 component is shown to arise from the second-layer Si atoms. The results are discussed in the context of structural models reported recently for other metal-induced Si(100)2x3 reconstructions. Finally, an atomic model is proposed for the 2x3-Eu phase.