Influence of the substrate lattice structure on the formation of Quantum Well States in thin In and Pb films on silicon

TL;DR

This study investigates how the lattice structure of silicon substrates affects the formation of quantum well states in thin indium and lead films, revealing that substrate-induced lattice relaxation and orientation changes significantly influence quantum state development.

Contribution

It demonstrates the critical role of substrate lattice relaxation and growth orientation in the formation of quantum well states in metal overlayers on silicon.

Findings

Quantum well states form only after indium layers relax to the bulk lattice structure.

Pb layers on Si(100) show inhibited quantum well states beyond 2 monolayers.

Substrate lattice structure strongly influences quantum well state formation.

Abstract

The substrate lattice structure may have a considerable influence on the formation of quantum well states in a metal overlayer material. Here we study three model systems using angle resolved photoemission and low energy electron diffraction: indium films on Si(111) and indium and lead on Si(100). Data are compared with theoretical predictions based on density functional theory. We find that the interaction between the substrate and the overlayer strongly influences the formation of quantum well states; indium layers only exhibit well defined quantum well states when the layer relaxes from an initial face-centered cubic to the bulk body-centered tetragonal lattice structure. For Pb layers on Si(100) a change in growth orientation inhibits the formations of quantum well states in films thicker than 2 ML.