Modelling nanostructures with vicinal surfaces

Abstract

Vicinal surfaces of the (111) plane of noble metals are characterized by free-electron-like surface states that scatter at one-dimensional step edges, making them ideal model systems to test the electronic properties of periodic lateral nanostructures. Here we use high-resolution, angle-resolved photoemission to analyse the evolution of the surface state on a variety of vicinal surface structures where both the step potential barrier and the superlattice periodicity can vary. A transition in the electron dimensionality is found as we vary the terrace size in single-phase step arrays. In double-phase, periodic faceted surfaces, we observe surface states that characterize each of the phases.

Lateral confinement effects of M¯-point Tamm state in vicinal Cu(100) surfaces

“…This means that the 2D surface states displaying superlattice band folding split into 1D quantum well levels with increasing terrace size (d) [12,[14][15][16][17][18][19][20]. The switching has been attributed to a decrease in the effective step barrier, due to the closing of the band gap after a critical miscut angle [12,14,21,22], or to localization induced by disorder [17].…”

Bridging the structure gap: Chemistry of nanostructured surfaces at well-defined defects

“…the recent review of Hammer [5]) and, on the other hand, to try using the steps as naturally nanostructured templates for the growth and self-assembling of ultra-thin films [6,7] and other nanosized structures for applications to nanoelectronics [8][9][10][11][12][13]. Among the aspects of HMI surfaces which captured the largest attention we mention: (a) the modification of the electronic properties due to the nanosized terrace width and to the reduced dimensionality of the system [14][15][16][17][18][19][20][21]; (b) the modification of the vibrational properties due to the additional phonons localized at the step edges [22][23][24][25][26][27][28][29]; (c) the roughening transition associated to step edge meandering [30][31][32][33][34][35][36]; (d) the modification of surface diffusion, impeded by the very presence of the steps and of the related Ehrlich-Schwoebel (ES) barriers [37][38][39][40][41][42]; (e) the intrinsic chirality of some step kinked surfaces, which may be of potential interest for heterogeneous asymmetric synthesis [43] and for the separation of enantiomers in enantio-sensitive reactions [44]…”

Determination of the photoelectron reference plane in nanostructured surfaces

“…Consequently, the Ag coverage has a direct influence on both the Ag and Cu stripe widths and on the local angle of the clean Cu facet (see figure 1). Confinement effects of Shockley states in these surfaces have already been reported [20,[23][24][25], exhibiting changes in the binding energy for both Ag and Cu surface states as a function of the stripe width and faceting periodicity, as well as changes in the photoelectron emission angle from the Cu stripes. In this work, we go a step beyond and introduce a Fourier analysis method of the ARPES data acquired for different photon energies (using synchrotron radiation) and periodicities (varying Ag coverage) so as to obtain the relevant reference direction of the surface electrons ejected from these uneven surfaces.…”