Composition and structure of Pd nanoclusters in SiO$_x$ thin film

TL;DR

This study investigates the formation, composition, and structure of Pd nanocrystals in SiO$_x$ thin films using microscopy and spectroscopy, revealing initial PdO$_x$ capping and decomposition into pure Pd upon heat treatment.

Contribution

It provides detailed insights into the nucleation, composition, and structural changes of Pd nanocrystals in SiO$_x$ films, including the effects of heat treatment.

Findings

Pd nanocrystals are initially capped by PdO$_x$ layers.

Heat treatment decomposes PdO into pure Pd nanocrystals.

XPS shows a 1-2 eV shift in Pd binding energy after heat treatment.

Abstract

The nucleation, distribution, composition and structure of Pd nanocrystals in SiO$_2$ multilayers containing Ge, Si, and Pd are studied using High Resolution Transmission Electron Microscopy (HRTEM) and X-ray Photoelectron Spectroscopy (XPS), before and after heat treatment. The Pd nanocrystals in the as deposited sample seem to be capped by a layer of PdO$_x$. A 1-2 eV shift in binding energy was found for the Pd-3d XPS peak, due to initial state Pd to O charge transfer in this layer. The heat treatment results in a decomposition of PdO and Pd into pure Pd nanocrystals and SiO$_2$.