Quantum size effect on dielectric function of ultrathin metal film: a first-principles study of Al(1 1 1)

Abstract

Quantum manifestations of various properties of metallic thin films by quantum size effect (QSE) have been studied intensively. Here, using first-principles calculations, we show quantum manifestation in dielectric properties of Al (111) ultrathin films. The QSE on the dielectric function is revealed, which arises from size dependent contributions from both intraband and interband electronic transitions. More importantly, the in-plane interband transitions in the films thinner than 15 monolayers are found to be smaller than the bulk counterpart in the energy range from 1.5 eV to 2.5 eV. This indicates less energy loss with plasmonic material of Al in the form of ultrathin film. Our findings may shed light on searching for low-loss plasmonic materials via quantum size effect.

First-principles study on surface stability of tantalum carbides

“…Accordingly, accounting three 5d electrons of Ta and two 2p electrons of C as the "free" valence electrons and using . This suggests a strong QSE in TaC (0 0 1) film with its surface properties oscillating in a period of three layers [17][18][19]40], in good agreement with our direct DFT calculations as shown in Fig. 2.…”

“…For metallic materials such as tantalum carbides, the electron Fermi wavelength is short (in the range of 3~5 Å) compared to semiconductors and insulators [16]. Consequently, pronounced quantum size effect (QSE) induced by electron quantum confinement is expected in their lowdimensional nanostructures [17], which poses substantial influences on electron charge density, work function, surface energy, surface stress, dielectric properties, and so on [18][19]. This also calls for a careful calculation of surface energies using the common thin slab method, consisting of adequate number of layers, because the surface energy may display an oscillating thickness dependency [17].…”

Electronic, Dielectric and Plasmonic Properties of Two-Dimensional Electride Materials X2N (X=Ca, Sr): A First-Principles Study

“…Dielectric function. The first-principles calculation based on DFT has proved to be a powerful tool for the study of dielectric function for metals, including ultrathin metallic films down to fewlayer thickness [33][34][35][36][37][38][39] . In crystalline solids, the dielectric function ε(ω) consists of two contributions: a Drude-like intraband contribution and an interband contribution.…”

Atomic-scale epitaxial aluminum film on GaAs substrate

“…1 With film thickness reduced from the nanometer scale to the atomic scale, a metal exhibits intriguing properties, due to so-called quantum size effect, and opens a window for fundamental science exploration and novel device development. [8][9][10][11][12] Unlike that in semiconductors, electronic quantum size effect in metals has been much more difficult to be observed because of its extremely short Fermi wavelength (< 1 nm). Driven by the huge potential of the quantized electronic/metallic states for various applications, searching for a practical and reliable method for preparing an atomic-scale metal film has been a long-standing challenge for material scientists and engineers.…”

“…Although there were theoretical works on the quantum size effect of Al, no clear corresponding ex-situ experimental evidences were reported. [9][10][11] In the present work, we use molecular beam epitaxy (MBE) to prepare a large-area, high-quality Al film of atomic-scale thickness. The Al films grown on GaAs (001) substrate were ex-situ characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), cross-sectional transmission electron microscopy (TEM), optical reflectivity and four-probe electrical measurements.…”