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The surface growth mechanisms of diamondlike carbon (DLC) films has been clarified. DLC films were synthesized in atmospheres with a fixed methane-to-argon ratio at different temperatures up to 700 °C by the photoemission-assisted glow discharge of photoemission-assisted plasma-enhanced chemical vapor deposition. The electrical resistivity of the films decreased logarithmically as the synthesis temperature was increased. Conversely, the dielectric constant of the films increased and became divergent at high temperature. However, the very high electrical resistivity of the film synthesized at 150 °C was retained even after post-annealing treatments at temperatures up to 500 °C, and divergence of the dielectric constant was not observed. Such films exhibited excellent thermal stability and retained large amounts of hydrogen, even after post-annealing treatments. These results suggest that numerous hydrogen atoms were incorporated into the DLC films during synthesis at low temperatures. Hydrogen atoms terminate carbon dangling bonds in the films to restrict π-conjugated growth. During synthesis at high temperature, hydrogen was desorbed from the interior of the growing films and π-conjugated conductive films were formed. Moreover, hydrogen radicals were chemisorbed by carbon atoms at the growing DLC surface, leading to removal of carbon atoms from the surface as methane gas. The methane molecules decomposed into hydrocarbons and hydrogen radicals through the attack of electrons above the surface. Hydrogen radicals contributed to the etching reaction cycle of the film; the hydrocarbon radicals were polymerized by reacting with other radicals and the methane source. The polymer radicals remained above the film, preventing the supply of the methane source and disrupting the action of argon ions. At high temperatures, the resultant DLC films were rough and thin.

The chemical structure of diamondlike carbon (DLC) films, synthesized by photoemission-assisted glow discharge, has been analyzed by Raman spectroscopy. Raman analysis in conjunction with the sp 2 cluster model clarified the film structure. The sp 2 clusters in DLC films synthesized at low temperature preferred various aliphatic structures. Sufficient argon-ion assist allowed for formation of less strained DLC films containing large amounts of hydrogen. As the synthesis temperature was increased, thermal desorption of hydrogen left carbon dangling bonds with active unpaired electrons in the films, and the reactions that followed created strained films containing aromatic sp 2 clusters. In parallel, the desorption of methane molecules from the growing surface by chemisorption of hydrogen radicals prevented the action of argon ions, promoting internal strain of the films. However, in synthesis at very high temperature, where sp 2 clusters are sufficiently dominant, the strain was dissolved gradually. In contrast, the DLC films synthesized at low temperature were more stable than other films synthesized at the same temperature because of stable hydrogen–carbon bonds in the films.

Ultraviolet photoelectron spectroscopy was used to measure the oxygen uptake, changes in work function due to the surface dipole layer of adsorbed-oxygen atoms, Δ ϕ SDL , and changes in band bending due to the defect-related midgap state, ΔBB, simultaneously during oxidation on Si(0 0 1) surface at room-temperature, RT, under an O 2 pressure of 1.3 × 10 −5 Pa. The oxygen dosage dependence of Δ ϕ SDL revealed that dissociatively adsorbed-oxygen atoms occupy preferentially dimer backbond sites at the initial stage of Langmuir-type adsorption, which is associated with a rapid increase of ΔBB. When raising temperature to ∼600 °C, such preferential occupation of the dimer backbond sites by oxygen atoms is less significant and ΔBB becomes smaller in magnitude. The observed relation between Δ ϕ SDL and ΔBB indicates that point defects (emitted Si atoms + vacancies) are more frequently generated by oxygen atoms diffusing to the dimer backbond sites at lower temperature in RT −600 °C.

The Si(001)c(4×4)-C surface, which was prepared by exposing a single-domain Si(001)2×1 surface to ethylene at a pressure of about 1×10 −6 mbar at 680°C for 600 s, was investigated by X-ray photoelectron diffraction (XPD). The azimuthal-scan XPD patterns of C 1s showed pronounced peaks due to the forward-focusing effect in XPD, indicating that the adsorbed carbon diffuses into the substitutional sites of at least the 4th layer below the surface. The anisotropies of the measured XPD patterns are analyzed by single-scattering-cluster (SSC) simulations to find that the highly concentrated Si 1− x C x alloy layers are present.

We have studied the desorption of indium from an In(∼1 ML)-adsorbed Si(001)-(1×2) surface at temperatures of 480–550°C by a combined method of reflection high-energy electron diffraction and Auger electron spectroscopy (RHEED-AES). Time evolutions of In coverage as monitored by AES showed that the desorption of In from two-dimensional (4×3) phase follows a half-order reaction scheme, in contrast to the previously proposed first-order reaction scheme. Parameters of the half-order desorption are determined. RHEED spot intensity profiles during desorption and the half-order desorption scheme are explained by a structural and morphological model.

The angular variation of the spin-orbit branching ratio of In 4d photoemission doublets from ordered In overlayers on the Si(001) surface was investigated. The branching ratios show strong angular anisotropy in the investigated photon energy range of 70–100 eV, which depends both on the surface structure and the photon energy. It is demonstrated that the anisotropy in this energy range is caused by an inherent difference in the photoelectron waves of the 4 d 5 2 and 4 d 3 2 levels via photoelectron diffraction.

Initial stage growth and interface formation of Al on a Si(001)2 × 1 surface has been studied by core-level and valence-band photoelectron spectroscopy using synchrotron radiation for the Al coverages ( Θ Al ) up to ∼2 ML at room temperature (RT) and 300°C. The measured Al 2p and Si 2p spectra reveal, for the first time, the existence of interfacial reaction of Al with Si in addition to the rather well-known dimer adsorption of Al. The reaction occurs even at RT for Θ Al ≥ 0.5 ML, which progresses significantly by annealing at 300°C from earlier stage of adsorption. Beyond 0.5 ML, Al 2p core levels indicate formation of Al clusters at both temperatures, which is accompanied by increase of the reacted phase. This interfacial reaction explains the 1 × 1 phase at 300°C found by LEED and the difference in band bending between RT and 300°C above ∼0.5 ML. The evolution of the valence-band surface electronic structures with respect to Θ Al is interpreted in a consistent way to the core-level results.

The electronic structure of a single-domain Si(001)2 × 2-Al surface has been studied by angle-resolved photoelectron spectroscopy (ARPES) using synchrotron radiation. Through detailed ARPES measurements along various symmetry axes of the surface Brillouin zone, the existence and dispersions of five surface states are identified, one at binding energies a little less than 1 eV and the others between 1 and 2 eV. The origin of the surface states are discussed in terms of the Al-dimer structures on Si(001).

We performed “in-situ” ultraviolet photoelectron spectroscopy (UPS) measurements during both solid-source and gas-source molecular-beam homoepitaxial growths on Si(100) surfaces. We found that the photoelectron intensity associated with surface states periodically oscillates during Si epitaxial growth. We demonstrate that the UPS intensity oscillation is associated with the alternation between the 2 × 1 and the 1× 2 surface reconstructions on the Si(100) surface, which resulted from Si layer-by-layer growth.

Kinetics of photon-stimulated-desorption (PSD) of positive ions from a Si surface treated with a hydrofluoric acid (HF) solution has been investigated using synchroton radiation (SR) in the vacuum-ultraviolet (VUV) region. Mass analysis of the PSD ions is performed with a time-of-flight technique. PSD of H+ and O+ ions is observed during exposure of the surface to VUV-SR. It is found that the O+ ion desorption rate initially rises and subsequently decreases as the amount of photon exposure is increased, while the H+ ion desorption rate decreases exponentially with photon exposure. The photon-exposure dependence of the O+ desorption rate is interpreted in terms of a two-step first-order process in which OH bond scission in a surface SiOH complex initially occurs to give rise to desorption of H+ and then the remaining Si-O bond is ruptured to produce O+ PSD ions. The H+ PSD reaction is found to be a single-step process.

Experimental results are presented on the synchrotron-radiation-induced desorption of oxygen ions from HF-treated Si surfaces measured with a quadrupole mass analyzer operated in the pulse-counting mode. The effect of atomic hydrogen exposure was studied. Desorption of H + , O + and F + ions was observed from HF-treated Si surfaces. The yield of O + ions was increased more than 30-fold by exposure to atomic hydrogen.