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Abstract. We recognize that the spreading of light at large distances (the whole space) is the only property which can decide by yes or no if light really behaves physically like waves, while the fit of the waves for describing the diffraction fringes is insufficient for this purpose. Indeed, the fringe space is too limited and hence, brings the possibility of misinterpretation. Hence, the experiment for the direct verification if light is spreading like waves at large distances is necessary in principle, and is crucial. However, very surprisingly and tragically, this direct experiment was totally missing in history. This experiment uses the simplest diffraction case, in which a beam of light falls perpendicularly with its axis on the line and the plane of a straight edge. Practically, this experiment verifies if there is a dependence of the diffracted light at large distances in the geometrical shadow, on the changes in beam thickness traversal to a single straight edge, while the distribution of light along the straight edge remains the same. If this dependence exists, as the wave theory for light fundamentally predicts, then the wave approach to light is physically true. If there is no dependence then light cannot behave physically like waves. This experiment can clearly be developed and performed without any calculation from the wave approach, just by a careful measurement practice. However, for a broader view, we describe in detail wave results for spreading of light at large distance, which illustrate the experiment – what are the spatial points where the measurement must be done to see if the above dependence exists, and which is the big picture for the wave approach. We attempted this experiment for many years, but could not finish it because of the lack of resources to measure at 100 – 500 m. However, we show alternatively that the answer to how light spreads also comes from comparing the well known wave results for the diffraction on macroscopic holes with relatively recent data for the diffraction on nanoscopic holes. This comparison clearly shows that light does not spread physically like waves, which makes necessary a new, non-wave but periodic structure for light. On this line, we show here the big-picture for developing this non-wave structure, that is a mechanism-type structure for light. With this new structure for light one can see that there is also a missing experiment at the foundation of gravity. Finally, the above alternative answer regarding the spreading of light also makes absolutely necessary to perform the above missing experiment, as a direct way that convinces anybody how light is spreading. The present article will empower big labs to perform this crucial experiment.

The ability of TiO2 to generate reactive oxygen species under UV radiation makes it an efficient candidate in antimicrobial studies. In this context, the preparation of TiO2 microparticles coated with Ca- and Cu-based composite layers over which Cu(II), Cu(I), and Cu(0) species were identified is presented here. The obtained materials were characterized by a wide range of analytical methods, such as X-ray diffraction, electron microscopy (TEM, SEM), X-ray photoelectron (XPS), and UV-VIS spectroscopy. The antimicrobial efficiency was evaluated using qualitative and quantitative standard methods and standard clinical microbial strains. A significant aspect of this composite is that the antimicrobial properties were evidenced both in the presence and absence of the light, as result of competition between photo and electrical effects. However, the antibacterial effect was similar in darkness and light for all samples. Because no photocatalytic properties were found in the absence of copper, the results sustain the antibacterial effect of the electric field (generated by the electrostatic potential of the composite layer) both under the dark and in light conditions. In this way, the composite layers supported on the TiO2 microparticles’ surface can offer continuous antibacterial protection and do not require the presence of a permanent light source for activation. However, the antimicrobial effect in the dark is more significant and is considered to be the result of the electric field effect generated on the composite layer.

We recognize that the spreading of light at large distances (the whole space) is the only property which can decide by yes or no if light really behaves physically like waves, while the fit of the waves for describing the diffraction fringes is insufficient for this purpose. Indeed, the fringe space is too limited and hence, brings the possibility of misinterpretation. Hence, the experiment for the verification if light is spreading like waves at large distances is necessary in principle, and is crucial. However, very surprisingly and tragically, this experiment was totally missing in history. This experiment uses the simplest diffraction case, in which a beam of light falls perpendicularly with its axis on the line and the plane of a straight edge. Practically, this experiment verifies if there is a dependence of the diffracted light at large distances in the geometrical shadow on the changes in beam thickness traversal to a single straight edge, while the distribution of light along the straight edge remains the same. If this dependence exists, as the wave theory for light fundamentally predicts, then the wave approach to light is physically true. If there is no dependence then light cannot behave physically like waves. This experiment can clearly be developed and performed without any calculation from the wave approach, just by a careful measurement practice. However, for a broader view, we describe in detail wave results for spreading of light at large distance, which illustrate the experiment – what are the spatial points where the measurement must be done to see if the above dependence exists, and which is the big picture for the wave approach. We attempted this experiment for many years, but could not finish it because of the lack of resources to measure at 100 – 500 m. The present article will empower big labs to perform this experiment. However, we show alternatively that the answer to how light spreads also comes from comparing the well known data for the diffraction on macroscopic holes with relatively recent data for the diffraction on nanoscopic holes. This comparison clearly shows that light does not spread physically like waves, which makes necessary a new, non-wave but periodic structure for light. Such an alternative answer regarding the spreading of light also makes absolutely necessary to perform the above missing experiment, as a direct way that convinces anybody how light is spreading.

Growth of Ag films of up to 30 nm thickness on Si(1 1 1) 7 × 7 at room temperature is investigated by low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). LEED revealed the coexistence of Ag and Si spots starting with 1 monolayer (ML) of Ag deposited. The Ag lattice constant, starting with 25 ML, is slightly higher than for bulk Ag and increase linearly with Ag thickness, reaching about 4.2 nm for the thickest films. The average terrace widths detected from LEED spot profile analysis are about 30 nm for clean Si(1 1 1) 7 × 7 and about 5.5 nm for the thickest Ag(1 1 1) film, in agreement with STM observations. The intensity variation of core levels analyzed by XPS is taken into account by a model assuming the initial formation of Ag islands with linear variation of coverage vs. the amount of Ag deposited, followed by growth in a quasi layer-by-layer mode. The interface barrier is in the range of 0.4 eV, lower than all values reported previously. Ag deposited on Si(1 1 1) 7 × 7 at room temperature provides flat Ag(1 1 1) for synthesis of 2D materials, and may be used for low barrier Schottky diodes.

We recognize that the spreading of light at large distances (the whole space) is the only property which can decide by yes or no if light really behaves physically like waves, while the fit of the waves for describing the diffraction fringes is insufficient for this purpose. Indeed, the fringe space is too limited and hence, brings the possibility of misinterpretation. Hence, the experiment for the verification if light is spreading like waves at large distances is necessary in principle, and is crucial. However, very surprisingly and tragically, this experiment was totally missing in history. This experiment uses the simplest diffraction case, in which a beam of light falls perpendicularly with its axis on the line and the plane of a straight edge. Practically, this experiment verifies if there is a dependence of the diffracted light at large distances in the geometrical shadow on the changes in beam thickness traversal to a single straight edge, while the distribution of light along the straight edge remains the same. If this dependence exists, as the wave theory for light fundamentally predicts, then the wave approach to light is physically true. If there is no dependence then light cannot behave physically like waves. This experiment can clearly be developed and performed without any calculation from the wave approach, just by a careful measurement practice. However, for a broader view, we describe in detail wave results for spreading of light at large distance, which illustrate the experiment – what are the spatial points where the measurement must be done to see if the above dependence exists, and which is the big picture for the wave approach. We attempted this experiment for many years, but could not finish it because of the lack of resources to measure at 100–500 m. The present article will empower big labs to perform this experiment. However, we show alternatively that the answer to how light spreads also comes from comparing the well known data for the diffraction on macroscopic holes with relatively recent data for the diffraction on nanoscopic holes. This comparison clearly shows that light does not spread physically like waves, which makes necessary a new, non-wave but periodic structure for light. Such an alternative answer regarding the spreading of light also makes absolutely necessary to perform the above missing experiment, as a direct way that convinces anybody how light is spreading.

Manganese is deposited at high temperature on (001) oriented ferroelectric lead zirco-titanate prepared in two different ways: sputter-annealed or just simply annealed in ultrahigh vacuum. Room temperature ferromagnetism (FM) is obtained for Mn deposited on sputter-annealed substrates, while for the other sample preparation a paramagnetic behaviour is obtained. Also, for the first case a clear inwards component of the polarization P(−) is observed by X-ray photoelectron spectroscopy and piezoresponse force microscopy. Composition analysis evidenced formation of Pb vacancies in the case of FM – P(−) sample, consistent with hole formation near the surface, needed both to stabilize the inwards polarization state and to intermediate ferromagnetism between Mn2+ ions. The indirect exchange ferromagnetism mediated by holes is stronger, most probably because the interaction energy is proportional with the carrier effective mass. Also, whereas in the case of unsputtered substrate a stable surface Mn oxide is formed, defect formation by sputtering seems to favor Mn migration inside the sample. This also induces the formation of a thin film where ferromagnetism and the orientation of ferroelectric polarization might have the same origin, i. e. holes accumulated near the outer surface.

By platinum deposition on a 150 nm thick film of lead zirco-titanate oriented PZT(001), grown on strontium titanate (001) single crystals with a strontium ruthenate buffer layer, which did not show initial preferential out-of-plane orientation of its ferroelectric polarization, a band bending near the interface towards lower energies is observed using photoelectron spectroscopy, by following all core levels from the substrate (Pb 4f, Zr 3d, Ti 2p, O 1s). This is unexpected given the fact that platinum has a larger work function than PZT and a rectifying contact for electrons is expected to be built at the interface. This observation may have two explanations: (i) platinum forms an alloy with elements from PZT yielding a metal with considerable lower work function; (ii) platinum provides electrons to the substrate which are able to compensate the depolarization field generated by the outwards polarization state. Several arguments are brought in favor of the second hypothesis, especially the attenuation of core levels from the substrate which is well described by exponential functions with reasonable values of the photoelectron inelastic mean free path, suggesting the formation of a sharp interface. High resolution transmission electron microscopy confirmed the sharpness of the interface.

We report the molecular beam epitaxy growth of Ni on a clean Ge(001) surface with an intermediate NiGe layer forming at the interface at room temperature. The crystallinity of the substrate is lost after the deposition of more than 2 Ni monolayers. The Schottky barrier formation is investigated by X-ray photoelectron spectroscopy. The method allows us to infer a 0.39–0.45 eV band bending at the interface between the compound and Ge(001). Magneto-optical Kerr effect measurements were conclusive in detecting the ferromagnetic ordering of Ni outermost layers.

Ni films of 20 nm nominal thickness were grown on Ge(001) substrates by molecular beam epitaxy at several different temperatures from room temperature up to 400 °C. X-ray diffraction and X-ray photoelectron spectroscopy reveal the nucleation of Ni-Ge compounds (NiGe, Ni 2 Ge, Ni 5 Ge 2 ) as well as a departure from the fcc Ni structure exhibited by the films at and beyond a temperature of 100 °C. The binding energy of the Ni 2p peak increases from the RT value (852.7 eV) by 0.5–1.1 eV for the Ni/Ge(001) samples, while the Ge 2p binding energy changes by 0.6–0.7 eV after Ni growth compared to a clean Ge(001) substrate (there is only a ±0.15 eV shift among the samples grown on substrates at higher temperatures). By increasing substrate temperature, we obtained higher intermixing of Ni and Ge, but rather than both Ni and Ge interdiffusing, we find that Ni diffuses further into the germanium with higher substrate temperature, forming increasingly Ni-rich Ni-Ge compounds diluted into the Ge matrix. Based on Magneto-optic Kerr Effect measurements, Ni/Ge(001) grown on substrates at 100 and 200 °C does not exhibit a hysteresis loop, while the samples on 300 and 400 °C substrates show magnetic behavior, which we attribute to the magnetic character of hexagonal Ni 5 Ge 2 (which is determined here for the first time to be a ferromagnetic phase).

We report the structural, electronic and magnetic investigation using extended X-ray absorption fine structure spectroscopy (EXAFS), photoelectron microscopy, spin-resolved photoemission and magneto-optical Kerr effect on the properties of Mn $$_{x}$$ Ge $$_{1-x}$$ systems obtained by molecular beam epitaxy deposition of manganese on Ge(001) wafers annealed on temperatures between 50 and 450 $$^{\circ }$$ C. Magnetic ordering can be achieved when the substrate temperature is higher than 250 $$^{\circ }$$ C, when the manganese tends to diffuse into the Ge matrix and segregate in Mn $$_{5}$$ Ge $$_{3}$$ -like compounds, as proved by EXAFS. High spatial resolution photoelectron spectroscopy reveals Mn inhomogeneities in the 5–10 $$\upmu $$ m range, even though Mn is found mostly in the same chemical state all over the surface.

We investigate band bending effects occurring at the interface between atomically clean Ge(001) and molecular beam epitaxy (MBE) deposited copper and platinum. Low energy electron diffraction (LEED) confirmed the crystallinity of the surface, evidenced the formation of (2 × 1) and (1 × 2) reconstructions, and revealed that it is strongly affected with metal deposition. X-ray photoelectron spectroscopy (XPS) data let us assume a Stranski–Krastanov growth mechanism and confirmed that the observed band bending is associated to an ohmic contact in both cases. For the platinum contact, the high values of the apparent inelastic mean free path (IMFP) derived from the evolution of the XPS intensities indicate a prevalence of mixture of Pt with Ge nearby the interface. Pt deposited on Ge(001) does not behave like a Schottky contact, as one may have expected due to the higher work function of platinum. The observed effect is similar to the case where interfacial Pt had a lower work function by 2.25/1.96 eV than that of metallic Pt. We propose a model to explain this fact by the effective mass variation or to the conduction band broadening due to the strong intermixing of platinum with germanium under the surface.

The positions of the low energy electron diffraction (LEED) spots from ferroelectric single crystal films depend on its polarization state, due to electric fields generated outside of the sample. One may derive the surface potential energy, yielding the depth where the mobile charge carriers compensating the depolarization field are located ($\ensuremath{\delta}$). On ferroelectric $\mathrm{Pb}(\mathrm{Zr},\mathrm{Ti}){\mathrm{O}}_{3}$(001) samples, surface potential energies are between 6.7 and 10.6 eV, and $\ensuremath{\delta}$ values are unusually low, in the range of $1.8\ifmmode\pm\else\textpm\fi{}0.4\phantom{\rule{0.16em}{0ex}}\AA{}$. When $\ensuremath{\delta}$ is introduced in the values of the band bending inside the ferroelectric, a considerably lower value of the dielectric constant and/or of the polarization near the surface than their bulk values is obtained, evidencing either that the intrinsic `dielectric constant' of the material has this lower value or the existence of a `dead layer' at the free surface of clean ferroelectric films. The inwards polarization of these films is explained in the framework of the present considerations by the formation of an electron sheet on the surface. Possible explanations are suggested for discrepancies between the values found for surface potential energies from LEED experiments and those derived from the transition between mirror electron microscopy and low energy electron microscopy.

Ferromagnetic FexGe1−x with x = 2%–9% are obtained by Fe deposition onto Ge(001) at high temperatures (500 °C). Low energy electron diffraction (LEED) investigation evidenced the preservation of the (1 × 1) surface structure of Ge(001) with Fe deposition. X-ray photoelectron spectroscopy (XPS) at Ge 3d and Fe 2p core levels evidenced strong Fe diffusion into the Ge substrate and formation of Ge-rich compounds, from FeGe3 to approximately FeGe2, depending on the amount of Fe deposited. Room temperature magneto-optical Kerr effect (MOKE) evidenced ferromagnetic ordering at room temperature, with about 0.1 Bohr magnetons per Fe atom, and also a clear uniaxial magnetic anisotropy with the in-plane easy magnetization axis. This compound is a good candidate for promising applications in the field of semiconductor spintronics.

Samarium is deposited on Si(001) at various temperatures (room temperature to 400 °C), and the surface structure, interface reactivity, electron configuration, and magnetic properties are investigated by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and magneto-optical Kerr effect (MOKE), respectively. It is found that metal Sm is present on samples prepared at room temperature with an interface layer containing mostly Sm2+ and a lower amount of Sm3+. When samples are prepared at high temperature, much less Sm0 is found with an increasing amount of Sm2+. Freshly prepared Sm0 and SmSi2 layers react strongly with oxygen from the residual gas, promoting formation of Sm2O3 at the expense of both metal Sm and SmSi2. Room temperature ferromagnetism is observed for all prepared layers with a decrease of the saturation magnetisation when samples are prepared at high temperature. It is found that ferromagnetism implies mostly Sm3+ and Sm metal. In addition to these findings, this work proposes a new assignment of the Sm 3d chemically shifted components. Also, a noticeable variation of the XPS Sm 3d spin-orbit splitting is found as a function of the Sm ionization state.

This study presents a correlated study of structural, reactivity, and magnetic properties of ultrathin Fe layers grown on Si(001) by molecular beam epitaxy in ultrahigh vacuum. The interface reactivity is characterized by Auger electron spectroscopy. The surface structure is characterized by low electron energy diffraction with spot profile analysis. The magnetism of the synthesized layers is investigated by magneto-optical Kerr effect. At room temperature, metal Fe layers with poor long-range order are synthesized; these layers are ferromagnetic with an extremely low coercitive field (below 1 Oe). The reactivity with Si is low in this case, with formation of an interface layer of about 8 A Fe equivalent thickness with about 7 at.% Si diffused. Samples synthesized at higher temperatures (500 °C) exhibit better long-range order, though the Fe reactivity with Si is higher and leads to the formation of an interface compound whose approximate stoichiometry is very close to Fe3Si. Once this compound is formed (for an equivalent Fe thickness of about 14 monolayers), disordered metal Fe islands are developing with subsequent Fe deposition, which contain also about 8 at.% Si diffused. These structures exhibit a much lower ferrimagnetism, with saturation magnetization about one order of magnitude lower than in the case of the room temperature synthesis. In this case of high temperature synthesis, two phases are observed, a ferrimagnetic one and a superparamagnetic one.

Clean Si(001) single crystal surfaces provided different surface reconstructions: p(1 × 2) and c(n × 2) (n = 4, 6) at room temperature. The in situ oxidation of these surfaces was followed by Auger electron spectroscopy and by X-ray photoelectron spectroscopy. It is found that, in similar ultrahigh vacuum conditions, much faster contamination (about 500 times) occurs when the samples are investigated by AES than by XPS, owing to the interaction of the electron beam with the sample surface. With the sample subject to the AES investigation, the contamination occurs by forming >Si2CO complexes based on the Si dimers. During XPS, reaction with water molecules from the residual gas should also be taken into account.

Transmission electron microscopy and X-ray photoelectron spectroscopy analyses are performed to investigate Ge nanoparticles embedded in an amorphous SiO2 matrix. GeSiO thin films are prepared by two methods, sol–gel and radio frequency magnetron sputtering. After the deposition, the sol–gel films are annealed in either N2 (at 1 atm and 800 °C) or H2 (at 2 atm and 500 °C), and the sputtered films in H2 (at 2 atm and 500 °C), to allow Ge segregation. Amorphous Ge-rich nanoparticles (3–7 nm size) are observed in sol–gel films. Crystalline Ge nanoparticles in the high pressure tetragonal phase (10–50 nm size) are identified in the sputtered films. The size of the nanoparticles increases with Ge concentration in the volume of the film. At the film surface, the Ge concentration is much larger that in the volume for both sol–gel and sputtered films. At the same time, at the film surface, only oxidized Ge is observed.

The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The “etch suppression” area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.

Applied surface science 267, 106 - 111 (2013). doi:10.1016/j.apsusc.2012.08.016, The surface structure, interface reactivity, electron configuration and magnetic properties of Sm layers deposited on Si(0 0 1) at various temperatures are investigated by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and magneto-optical Kerr effect (MOKE). It is found that metal Sm is present on samples prepared at low temperature, with an interface layer containing SmSi2 and Sm4Si3. When samples are prepared at high temperature, much less metal Sm is found, with an increasing amount of SmSi2. Room temperature ferromagnetism is observed for all prepared layers, with a decrease of the saturation magnetization when samples are prepared at high temperature. It is found that ferromagnetism implies mostly a compound with approximate stoichiometry Sm4Si3. Also, the decrease in the intensity of the XAS 2p3/2 → 3d white lines with the corresponding increasing amount of SmSi2 may be explained by assuming a higher occupancy of Sm 5d orbitals (5d2 configuration), most probably due to hybridation effects., Published by North-Holland, Amsterdam

“Rolled‐up” nanostructures formed from lattice mismatched III‐V heterojunction films by taking advantage of a strain‐induced self‐rolling mechanism represent a useful type of building blocks for nanotechnology, with possible applications in high‐speed microelectronic and optoelectronic devices. This work investigated the effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up MBE grown InGaAs/GaAs bilayers. Based on this “etch suppression effect” (ESE), we propose an illumination‐assisted technique that offers an advantage over other methods of rolling up nano‐objects on a substrate from inherently strained films because it allows control over the positioning of rolled‐up micro‐ and nanotubes independently from lithographic methods. For thicknesses of AlAs below 10 nm, we found two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds...

Atomic layer deposition and magnetron sputter deposition were used to synthesize thin-film multilayers of W/Al 2 O 3 . With individual layers only a few nanometers thick, the high interface density produced a strong impediment to heat transfer, giving rise to a thermal conductivity of ∼0.6 watts per meter per kelvin. This result suggests that high densities of interfaces between dissimilar materials may provide a route for the production of thermal barriers with ultra-low thermal conductivity.

The thermal conductance of interfaces between epitaxial TiN and single crystal oxides is measured at temperatures between 79.4 and 294 K using time-domain thermoreflectance. The analysis method relies on the ratio of the in-phase and out-of-phase signals of the lock-in amplifier for more accurate data analysis. The validity of this approach is tested by measurements on 6.5, 11.8, and 25 nm thick thermally oxidized ${\mathrm{SiO}}_{2}$ on Si. The thermal conductances G of TiN/MgO(001), TiN/MgO(111), and ${\mathrm{T}\mathrm{i}\mathrm{N}/\mathrm{A}\mathrm{l}}_{2}{\mathrm{O}}_{3}(0001)$ interfaces are essentially identical and in good agreement with the predictions of lattice dynamics models and the diffuse mismatch model with a four-atom fcc unit cell. Near room temperature, $G\ensuremath{\approx}700{\phantom{\rule{0ex}{0ex}}\mathrm{M}\mathrm{W}\mathrm{m}}^{\ensuremath{-}2}\phantom{\rule{0ex}{0ex}}{\mathrm{K}}^{\ensuremath{-}1},$ $\ensuremath{\approx}5$ times larger than the highest values reported previously for any individual interface.

Thermal conductivities of hydrogen-silsesquioxane thin films---Dow Corning ``flowable oxide'' and nanoporous ``extra-low-$k''$ spin-on dielectrics---are measured in the temperature range 80--400 K using the $3\ensuremath{\omega}$ method. Film thickness and atomic densities are characterized by the combination of Rutherford-backscattering spectrometry and variable-angle spectroscopic ellipsometry. Measurements of the longitudinal speeds of sound by picosecond ultrasonics and interferometry enable comparisons with the model of the minimum thermal conductivity of homogeneous materials. This model fails to capture the strong temperature dependence of the conductivity. Data for nanoporous silsesquioxane and ${\mathrm{SiO}}_{2}$ are compared to the predictions of effective medium theories of heterogeneous materials. Differential-effective-medium theory predicts a scaling of thermal conductivity $\ensuremath{\Lambda}$ with atomic density n, $\ensuremath{\Lambda}\ensuremath{\propto}{n}^{3/2}$ in good agreement with experiment. The comparisons with effective-medium theories suggest that a greater control of pore microstructure may enable significant improvements in the thermal and mechanical properties of porous dielectrics.