Structure and optical properties of Cd substituted ZnO (Zn1-xCdxO) nanostructures synthesized by high pressure solution route

TL;DR

This study synthesizes Cd-doped ZnO nanostructures via high pressure solution growth, revealing structural and optical changes such as increased unit cell volume and red-shifted photoluminescence due to strain and phase separation.

Contribution

It introduces a high pressure solution synthesis method for Cd-doped ZnO nanostructures and analyzes their structural and optical properties in detail.

Findings

Unit cell volume increases with Cd concentration.

Photoluminescence exhibits a red shift with Cd substitution.

Phase separation influences PL linewidth and strain distribution.

Abstract

We report synthesis of Cd substituted ZnO nanostructures (Zn1-xCdxO with x upto \approx .09) by high pressure solution growth method. The synthesized nanostructures comprise of nanocrystals that are both particles (~ 10-15 nm) and rods which grow along (002) direction as established by Transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis. Rietveld analysis of the XRD data shows monotonous increase of the unit cell volume with the increase of Cd concentration. The optical absorption as well as the photoluminescence (PL) shows red shift on Cd substitution. The line width of the PL spectrum is related to the strain inhomogenity and it peaks in the region where the CdO phase separates from the Zn1-xCdxO nanostructures. The time resolved photoemission showed a long lived (~10ns) component. We propose that the PL behavior of the Zn1-xCdxO is dominated by strain in the sample with the redshift of the PL linked to the expansion of the unit cell volume on Cd substitution.