We have investigated a Ge δ-doped layer in Si(001) formed by solid phase epitaxy (SPE) using time-of-flight low-ener-gy ion scattering spectroscopy (TOF-LEIS). The Ge δ-doped layer was formed by annealing a Si buffer layer deposited on a Ge(1ML)/Si(001) surface. We found that Ge atoms diffuse from the δ-doped layer around the interface as a result of SPE growth of the Si buffer layer. Incident angle dependence of Ge and Si intensities at various annealing temperatures showed that the Ge atoms began to occupy Si lattice sites above 300°C; indicating Ge-Si alloying near the interface region, and that the diffusion of Ge atoms was promoted above 500°C accompanied by the crystallization process of the Si buffer layer. The thickness of the Si1-xGex layer at 600°C was estimated to be about 30 Å, where the Si buffer layer was nearly perfectly crystallized.
The surface of polytetrafluoroethylene (PTFE) was modified hydrophilically by the bombardment of positive ions formed by introducing water into an ion source (H2O ion bombardment). The contact angle of water on the PTFE was changed from 120° to 0° by H2O ion bombardment with 0.6×1016 ions/cm2. In this range, the surface roughness of the PTFE was not changed. XPS analysis showed that OH-groups were created on the surface. Copper thin film was deposited on the PTFE surface after H2O ion bombardment, and the bonding strength between the Cu thin film and PTFE increased in pro-portion to the quantity of ion bombardment. At H2O ion bombardment with 1.2×1016 ions/cm2, the bonding strength was 12MPa. Our experimental results suggest that the oxide layer of the Cu thin film and the OH-groups of the PTFE surface are connected by hydrogen bridges.
Adsorption structures of CO and NO on the NiO(111) film grown on Ni(111) crystal have been investigated by sum frequency generation (SFG) spectroscopy and infrared reflection absorption spectroscopy (IRAS). The CO stretching band of adsorbed CO on NiO(111) was observed at 2144 cm-1 on the SFG spectra for both p- and s-polarized visible light. However, adsorbed NO on NiO(111) was observed at 1805 cm-1 on the SFG spectra only for the p-polarized visible light. The results suggest that the adsorbed CO molecule was tilted from the surface normal but the NO molecule was perpendicular to the surface. These orientations of CO and NO reflect the surface structure of NiO(111) which has (2×2)reconstructed microfacets. Adsorption of CO on Ni(111) instead of NiO(111) was also examined by SFG and IRAS. Absorption bands due to linear and bridged CO were observed at 2076 and 1918 cm-1, respectively, by IRAS. On the other hand, the linear CO molecules on Ni(111) gave an SFG peak at 2076 cm-1 only for the p-polarized visible light indicating the CO molecules are perpendicular to the surface, and bridged CO molecules did not give any SFG signal. The absence of the bridged CO signal is believed to be due to the smaller Raman tensor of bridged CO.
We evaluated the throughput of a Schwarzschild soft X-ray objective for scanning photoelectron microscopes. It was found that the objective has the maximum throughput of 9% at a photon energy of 87 eV. Based on the results, we discuss an application to scanning photoelectron microscopy using this objective combined with a synchrotron radiation source.
The decomposition of the surface formate on Ni(110) was studied by temperature programmed desorption (TPD) and timeresolved infrared reflection absorption spectroscopy (TR-IRAS). It was observed that dehydration proceeded simultaneously with dehydrogenation. The rate-determining step of dehydration was found to be the C-H bond cleavage of formate as is the case of dehydrogenation by analysis of the kinetic isotope effect using HCOO(a) and DCOO(a). These results suggest that the rate-determining steps of dehydration and dehydrogenation are common. We propose a mechanism in which the CO2(a) species formed via the C-H bond cleavage of formate acts as the intermediate not only for dehydrogenation but also for dehydration; dehydration takes place by dissociation of the C-O bond of CO2(a).
We have studied an experimental method to evaluate the penetration depth of total-reflection x-rays, which is an important factor for total-reflection x-ray analysis. The penetration depth can be evaluated by measuring the takeoff-angle dependence of x-ray fluorescence. We have developed a new glancing-incidence and glancing-takeoff x-ray analytical apparatus. Using this apparatus, we evaluated the penetration depth of Mo Kα into a GaAs wafer. The experimental results agreed well with the theoretical penetration depth.
The behavior of monolayer-deep holes on the surface of (001) GaAs during post-growth annealing in molecular beam epitaxy was observed by in-situ scanning electron microscopy. Most small holes disappear immediately after growth. However, it was found that some are left and combine to form big holes. They extend in the  direction and coalesce with each other, while at the same time, shrink in the  direction. Finally, they shrink in both directions and disappear. It takes about 10min for all the holes to disappear, which is much longer than the growth interruption period usually employed to smooth heterointerfaces. The anisotropic behavior of big holes is discussed in relation to the reported growth anisotropy.
The adsorption and decomposition of formic acid on a (2×2)-NiO(111) surface were studied by TPD and IRAS under ultrahigh vacuum conditions. It was found by TPD that formic acid decomposed to hydrogen and carbon dioxide at 340-390 and 520 K and to carbon monoxide at 415 and 520 K. An IRA spectra showed that the formic acid adsorbs dissociatively to form formate in a tilted-bidentate configuration. It is known that adsorbed CO on NiO(111) gives two IRAS peaks, of which the peak at the higher wavenumber is assigned to the CO on fully-oxidized Ni cation sites and that at lower fre-quency to the CO on less-oxidized sites. The less-oxidized sites are considered to be located at oxygen vacancy, boundaries of the NiO crystals, and/or steps. We examined the IRA spectra of adsorbed CO on the formate-covered NiO(111) at 100 K after heating to various temperatures to characterize the reaction sites of formate giving each TPD peak. When the formate-covered NiO(111) was heated to 340-415 K, the higher frequency band of adsorbed CO appeared, indicating that the decomposition of formate at 340-415 K takes place on the fully-oxidized sites. On the other hand, the intensity of the CO band at lower frequency increased above 473 K, and the decomposition of formate at 520 K was considered to arise from the less-oxidized sites.
Adsorption of ethylene on bare and ethylidyne-covered Pt(111) surfaces in the presence of gaseous ethylene was investigated using infrared reflection absorption spectroscopy (IRAS). An IRAS peak at 954 cm-1 from ethylene was reversibly adsorbed on the bare Pt(111) at 10 Ton and 150∼180 K which was assigned to the C-H out-of-plane bending mode of n bonded ethylene. The heat of adsorption of π-bonded ethylene on Pt(111) was estimated to be 35±10 kJ/mol from the analysis of the adsorption isobar. On the ethylidyne-covered Pt(111), reversibly adsorbed π-bonded ethylene was also observed under the same condition where an IRAS peak at 954 cm-1 appeared. The adsorption of π-bonded ethylene on ethylidyne-covered Pt(111) was weaker than that on the bare Pt(111).