Adsorbate-Mediated Growth of Rare-Earth Oxides on Silicon

TL;DR

This study demonstrates that chlorine passivation enables the epitaxial growth of high-quality, ultrathin cerium oxide films on silicon by suppressing undesirable interface reactions, with implications for advanced silicon-based oxide layers.

Contribution

It introduces a passivation method using chlorine to achieve epitaxial, high-quality rare-earth oxide films on silicon, improving interface control and film crystallinity.

Findings

Cl passivation results in highly crystalline REOx films

Cl effectively suppresses silicate and silicon oxide formation

Cl passivation enables growth of superior ultrathin lanthana and ceria films

Abstract

Ultrathin cerium oxide films have been deposited on chlorine, gallium, and silver passivated Si(111) by reactive molecular beam epitaxy in a comparative study. The crystallinity of these films has been characterized by x-ray standing waves while the oxidation state of the rare-earth oxide (REOx) films and the chemical interface composition have been revealed by hard x-ray photoelectron spectroscopy. The use of Cl as passivating agent results in the epitaxial growth of highly crystalline REOx films with the RE metal in the 3+ oxidation state while effectively suppressing silicate and silicon oxide formation at the interface. In contrast, Ga and Ag preadsorption yield films of inferior quality, in the case of Ag of even lower crystallinity than without passivation. Further investigations show that Cl-passivation also results in ultrathin lanthana films of superior quality, which facilitate the growth of well-ordered ceria on lanthana REOx multilayers.