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The line shape of the photoelectron spectrum emitted from the sp-derived surface state at I on Cu(111) is investigated. The line shape is Lorentzian, and the temperature dependence of the width is linear, varying from 30 meV at 30 K to 75 meV at 625 K. Less than 5-rneV variation with binding energy is observed. The temperature dependence is explained as the phonon contribution to the inverse hole lifetime, predicted to be 2~kkbT allowing the determination that the electron-phonon mass enhancement parameter X. = 0.14~0.02 for this surface state at I . This is compared to X =0.15 reported as an average over the bulk Fermi surface.In the standard picture of angle-resolved photoemission spectroscopy, the peak width observed from a perfect crystal with negligible dispersion of the hole state perpendicular to the surface is equal to the inverse hole lifetime fi, /r. ' A measurement of linewidth as a function of binding energy, temperature, and impurity concentration determines the dependence of the hole lifetime on these variables. If the measurements are done at hole energies relatively close to the Fermi energy EF then one can compare to determinations based on low-energy techniques, such as Fermi surface probes, conductivity, and specific-heat measurements. The photoemission measurement is in many ways superior to these other techniques. It is more direct, involves no Fermi surface averaging, and does not depend on assumptions about one-electron theory. Photoemission also has the unique advantage that the energy dependence of the lifetime is directly observable. Its well-known surface sensitivity of a few atomic layers is both an advantage and a disadvantage. On the one hand, surfaces can be studied, while, on the other hand, comparison with bulk sensitive techniques is complicated. Photoemission is also a complex many-body process, allowing some uncertainty about the degree to which the standard picture of identifying widths with inverse hole lifetimes is correct. ' To date, there has been very little successful comparison of valence photoemission linewidths and inverse hole lifetimes, some notable failures of this identity, and some controversy. ' ' ' We report here quantitative understanding of the temperature dependence of the linewidth of a Cu(111) surface state based on the phonon contribution to the hole lifetime. In addition, we describe a surface sensitive method of determining one of the most ubiquitous parameters of solid-state physics, P, the electron-phonon mass enhancement parameter.There are three processes that contribute to valence hole decay at zero temperature in metals. One is Auger decay, where one hole decays into two less tightly bound holes and an electron via the electron-electron interaction (electronhole pair creation). The second is phonon scattering, where one hole decays into a less tightly bound hole plus a phonon via the electron-phonon interaction (phonon creation). The third is scattering by an impurity or defect from one momentum to another at fixed energy. At finite temperature,...

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We report the measurement of , the electron-phonon mass enhancement parameter, for the spin-orbit-split ⌫ surface state on Au͑111͒. is determined from the change of the photoemission linewidth as a function of temperature. The difference between the normal emission = 0.34± 0.01 and midband = 0.30± 0.01 is explained as increasing bulk penetration of the surface state as it approaches the Fermi level. DOI: 10.1103/PhysRevB.74.033410 PACS number͑s͒: 73.25.ϩi, 71.70.Gm, 73.20.At, 79.60.Ϫi Low-energy excitations in solids are fundamental to life as we know it. They determine quantities such as conduction and specific heat, which are important properties for things as common as how high the electric bill is. One type of low-energy excitation is the electron-phonon interaction. Understanding the electron-phonon interaction helped unlock the door to the description of traditional superconductivity and may be fundamental to understanding the mechanism of the more technologically exciting high-T c superconductors.As electromechanical miniaturization progresses and the number of surface atoms becomes comparable to the number of bulk atoms for a given sample or device, surface properties are becoming more and more important. The combination of the increasing importance of surface properties and an interest in the electron-phonon interaction has led to a significant increase in research in this area. See the reviews by Plummer et al.1 and Kevan and Rotenberg 2 and references therein.In 1995 McDougall et al. 3 published a seminal paper on the use of photoemission spectroscopy to measure , the electron-phonon mass enhancement parameter. The relevant theory is as follows. The contributions to the hole lifetime and therefore to the total photoemission linewidth, are electron-electron, electron-phonon, and electron-impurity scattering. Electron-impurity scattering is not temperature dependent and the temperature dependence of electronelectron scattering is negligible. For temperatures T with k b T greater than phonon energies the temperature dependence of the photoemission linewidth W should be almost entirely due to the electron-phonon interaction which has the temperature-dependent linewidthThus, can be measured by plotting W vs T and measuring the slope. is formally defined right at the Fermi level ͑E F ͒; 4 therefore, the term is used somewhat loosely here. Nevertheless, for the reasons given above the present data do in fact provide a direct indication of the strength of the electron-phonon interaction near E F . has been measured on the ͑111͒ surfaces of the other noble metals copper 3,5,6 and silver; 6 however, we are not aware of any measurements of on Au͑111͒. We present here data from the ⌫ surface state on Au͑111͒.The Au͑111͒ surface has been the subject of much research due to its well-known herringbone reconstruction 7-13 and the more recent discovery of the spin-orbit splitting of the ⌫ surface state. [14][15][16][17][18] The dispersion of the spinorbit-split surface state can be described as a pair of parabolas...

We have developed a 3D MOSCAP to characterize sidewall dielectric electrical performance to help gauge the quality and reliability of non-planar devices, such as FinFETs. The 3D MOSCAP can be used for process and materials development for high-Κ metal gate, spacer, and liner applications for 3D monolithic integration for future generation devices. In comparison, a traditional 2D (planar) MOSCAP is for characterization of dielectrics in the horizontal plane only. This study used different oxides as examples to compare the sidewall dielectric quality and electrical performance, and compare with that of oxide on a horizontal surface. A data analysis methodology is developed and demonstrated to extract sidewall dielectric properties from measured electrical results.

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