Size effects in IR-optical properties of ultrathin Pb quantized films

TL;DR

This study investigates how the optical reflectance of ultrathin lead films on a silicon surface varies with film thickness, revealing quantum size effects through polarization-dependent measurements in the infrared range.

Contribution

It provides the first detailed measurement of the dielectric tensor component parallel to the surface in ultrathin Pb films, demonstrating quantum size effects with monolayer resolution.

Findings

Oscillations in dielectric function component due to quantum size effects

Quantum size effects observed with a period of 2 monolayers

Reflectance difference varies systematically with film thickness

Abstract

The reflectance difference (RD) as a function of film thickness was measured during Pb deposition on Si(111)-(6x6)Au surface at 105 K. The oblique incident s- and p-polarized light with energy range 0.25-0.60 eV was used. The component of the dielectric function tensor parallel to the surface was determined from the data of experiments and it oscillation due to quantum size effects (QSE) with period of 2 ML within the Pb monolayer-by-monolayer growth was observed.