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The Sn/Ge(111) interface has been investigated across the 3 x 3 -->, root 3 x root 3 R30 degrees phase transition using core level and valence band photoemission spectroscopies. We find, both above and below the transition, two different components in the Sn 4d core level and a bond splitting in the surface state crossing the Fermi energy. Theoretical calculations show that these two effects are due to the existence of two structurally different kinds of Sn atoms that fluctuate at room temperature between two positions and are stabilized in a 3 x 3 structure at low temperature.

The Ge(111)-I surface has been studied at different I coverages ranging from 0.05 ML up to saturation, and different annealing temperatures, using photoelectron spectroscopy (PES) and scanning tunneling microscopy (STM). At saturation the surface is covered with I in the top site and GeI2 species in the bridge site, coexisting with small islands/clusters comprising GeI2, giving a total coverage of I in GeIx species of 1.15 ML. The chemically induced shifts in the Ge 3d core level are 0.39 eV per attached I atom. The coverage determined from the I 4d core level is higher than 1.15 ML, which we explain by the presence of I not bound to Ge. Annealing at 200°C decreases the iodine coverage, whereas the I 4d and Ge 3d line profiles are practically unchanged. Further heating desorbs the iodide species and restores the virgin c(2 × 8) structure.

Angle-resolved ultraviolet photoelectron spectroscopy has been used to study the electronic structure of a Si(110)2×3-Sb surface. The surface shows a semiconducting behavior with the highest occupied surface-state band observed around 1.8 eV below the Fermi level (EF). A second state is observed at Γ at 2.2 eV below EF dispersing >2.0 eV towards higher binding energies along the [110] and [111] directions. A third state is observed along the [111] direction around the M point. Surface differential reflectivity experiments showed no optical transitions up to an energy of 3.5 eV, indicating that the minimum energy position of the lowest empty band must be at least 1.8 eV above EF.

Go-adsorption of tin and potassium is found to induce a 3x1 reconstruction on the Ge(lll) surface. A very small amount of tin influences the Ge 3d core level spectra substantially compared to the G ...

The electronic properties of clean Si(110)16 × 2 and Si(110)2 × 3-Sb surfaces have been studied by angle resolved ultraviolet photoelectron spectroscopy (ARUPS) and surface differential reflectivity (SDR). For the clean 16 × 2 surface four surface states have been recognized by ARUPS and their dispersions have been mapped along the main symmetry lines in the surface Brillouin zone. SDR experiments revealed transitions between filled and empty surface states at ∼ 1.8, 2.4 and 2.9 eV. Antimony has been subsequently evaporated (about one monolayer) thus obtaining a 2 × 3 reconstruction. The surface electronic structure resulted to be strongly modified with three surface state bands observed in ARUPS along the [ 1 11] direction and no optical transitions detected by SDR in our energy range (1.3–3.5 eV).

The electronic properties of clean Si(110)16x2 and Si(110)2x3Sb surfaces have been studied by Angle Resolved Ultraviolet Photoelectron Spectroscopy (ARUPS) and Surface Differential Reflectivity (SDR). For the clean 16×2 surface four surface states have been recognized by ARUPS and their dispersions have been mapped along the main symmetry lines in the surface Brillouin zone. SDR experiments revealed transitions between filled and empty surface states at ∼1.8, 2.4 and 2.9 eV. Antimony has been subsequently evaporated (about one monolayer) thus obtaining a 2×3 reconstruction. The surface electronic structure resulted to be strongly modified with only two surface state bands observed in ARUPS and no optical transitions detected by SDR in our energy range (1.3–3.5 eV).

We have studied by ellipsometry the surface optical response of clean reconstructed Ge(111) between room temperature and a value very close to the melting point. By scanning the temperature at constant wavelength we detected three reversible surface phase transitions. The first is the well known c(2 × 8)−(1 × 1) transition around 250°C. A second one occurs between 700 and 750°C and is probably related to the order-disorder transition reported by McRae (Phys Rev Lett, 58 , 1437 (1987)). The third transition at about 70°C below the bulk melting point is detected for the first time.

The growth of silver on Si(111) is reexamined and new experiments are carried out using the method of isothermal desorption spectroscopy with AES. A correlation between LEED patterns and AES data upon adsorption and desorption permits one to precise the domain of existence of both 3 × 1 and √3 phases (respectively completed at 1 3 and 2 3 of a monolayer) and therefore to draw a 2D phase diagram and propose new structural models. We extend a kinetic model proposed earlier for the case of desorption of 2D phases, to the desorption of 3D crystallites. We thus show that using a simple kinetic method, thermodynamic parameters may be directly derived, namely the cohesive energy and the vibrational frequency of each phase. The values obtained, close to the ones of bulk silver, are respectively: E = 68 kcalmole−1, ν = 2.3 × 1012s−1 for the 3 × 1 phase; E = 65 kcalmole−1, ν = 1.8 × 1012s−1 for the √3 phase; E = 67 kcalmole−1, ν = 4 × 1012s−1 for the 3D crystallites.

The electronic properties of a clean Si(110)‐16×2 surface have been studied by angle resolved ultraviolet photoelectron spectroscopy (ARUPS) and surface differential reflectivity (SDR). Four surface states have been recognized by ARUPS and their dispersions have been mapped along the main symmetry lines in the surface Brillouin zone. SDR experiments revealed transitions between filled and empty surface states at ∼1.8, 2.4, and 2.9 eV. The results have been explained on the basis of a new structural model of the Si(110) 16×2 phase using adatoms, rest atoms and dimers as building blocks similarly to the case of the Si(111) 7×7 dimer‐adatom‐stacking fault (DAS) model.