Probing Interface Electronic Structure with Overlayer Quantum-Well Resonances:Al/Si(111)

Abstract

The dispersion of quantum-well resonances in ultrathin epitaxial Al films on Si(111) reveals energy- and wave vector-dependent reflection properties at the Al/Si interface. The substrate electronic structure strongly influences the phase shift of the electron waves upon reflection at the interface. Thus the details of the substrate electronic structure need to be taken into account for a complete analysis of metallic quantum-well resonances. Furthermore, the assumption of loss of parallel wave vector information upon reflection or transmission through a lattice-mismatched interface is challenged. The changes induced in the electronic structure of the overlayer can be used to probe the ground-state substrate band edges.

Controlling the effective mass of quantum well states in Pb/Si(111) by interface engineering

“…Electronic states further away from the VB are not affected. The interaction of film states with the VB of the substrate was also reported for Al/Si(111) 34 and Ag/Ge(111) 35 and explained in terms of hybridization of the film and valence states of the substrate. States within the specific momentum range around Γ are quantum resonances, because they are not confined within the absolute band gap of Si(111).…”

Quantum Size Effects Induced Novel Properties in Two-Dimensional Electronic Systems: Pb Thin Films on Si(111)

“…The QWS has been already widely explored in metal films, such as Ag, 6) Mg, 7) Fe, 8) and other metals, 9) and the QSE on material properties, such as Hall effect, 10,11) superconductivity, 12,13) resistivity, 14) thermal stability, 15) have been reported. The QSE on growth behaviors has also been studied.…”

Probing Quasiparticle States Bound by Disparate Periodic Potentials

“…Alternatively, in artificially ordered 2D heterojunctions [13] or tunnel junctions [14], relevant for nanoelectronics and spintronics, electrons are coherently transported between two structures of different periodicities. Besides being of practical interest, these systems raise attractive and unresolved fundamental questions on how their electronic structure depends on the translational mismatch, the difference in the potential strength between the crystalline structure of the two constituents, and the dissimilarity of the electronic structure.We notice that recently, several photoemission experiments focused on QW states of noble and simple metal layers on semiconductors, aiming at the understanding of coupling effects among film and substrate electronic states [15][16][17]. The difference in the lattice parameters between metals and semiconductors does not necessarily hinder a single-crystal film growth but often results in very large unit cells or incommensurate structures.…”

“…Moreover, the difference in the point group symmetry of these metals and the diamond or zinc-blende semiconductors implies that the interaction between bands with common symmetry has to be limited to particular regions in the momentumenergy space. QW states display in several systems an enhancement of the effective electron mass arising from the hybridization between substrate and metal states [15,16]. The interactions with the substrate most remarkably result in discontinuities of the QW dispersionobservable, also in relatively thick films, when the QW states cross the upper edge of the semiconductor valence band and enter into a k-projected energy gap [16,17].…”