Growth kinetics and atomistic mechanisms of native oxidation of ZrS$_x$Se$_{2-x}$ and MoS$_2$ crystals

TL;DR

This study investigates the oxidation behaviors of ZrS$_x$Se$_{2-x}$ alloys and MoS$_2$, revealing how composition influences oxidation rates and elucidating atomistic mechanisms crucial for semiconductor device design.

Contribution

It provides the first detailed analysis of oxidation kinetics and atomistic mechanisms in ZrS$_x$Se$_{2-x}$ alloys and MoS$_2$, highlighting the role of Se content and surface chemistry.

Findings

ZrS$_x$Se$_{2-x}$ oxidize rapidly with Se content increasing oxidation rate.

Oxidation involves Zr-O bond switching and van der Waals gap collapse.

MoS$_2$ remains stable due to unfavorable oxygen adsorption.

Abstract

A thorough understanding of native oxides is essential for designing semiconductor devices. Here we report a study of the rate and mechanisms of spontaneous oxidation of bulk single crystals of ZrS$_x$Se$_{2-x}$ alloys and MoS$_2$. ZrS$_x$Se$_{2-x}$ alloys oxidize rapidly, and the oxidation rate increases with Se content. Oxidation of basal surfaces is initiated by favorable O$_2$ adsorption and proceeds by a mechanism of Zr-O bond switching, that collapses the van der Waals gaps, and is facilitated by progressive redox transitions of the chalcogen. The rate-limiting process is the formation and out-diffusion of SO$_2$. In contrast, MoS$_2$ basal surfaces are stable due to unfavorable oxygen adsorption. Our results provide insight and quantitative guidance for designing and processing semiconductor devices based on ZrS$_x$Se$_{2-x}$ and MoS$_2$, and identify the atomistic-scale mechanisms of bonding and phase transformations in layered materials with competing anions.