Effect of rapid thermal annealing on short period {CdO/ZnO}m SLs grown on m-Al2O3

TL;DR

This study investigates how rapid thermal annealing at 900°C affects the structural and compositional properties of CdO/ZnO superlattices grown on m-Al2O3, revealing atom migration and optical property changes.

Contribution

It provides new insights into the effects of high-temperature annealing on CdO/ZnO superlattices, including atomic migration, segregation, and optical emission shifts.

Findings

Cd atom migration occurs after annealing at 900°C.

Cd distribution depends on layer thicknesses.

Optical emission peaks shift with Cd profiles.

Abstract

Here, we report on the characterization of {CdO/ZnO}m superlattice structures (SLs) grown by plasma assisted molecular beam epitaxy. The properties of as-grown and annealed SLs deposited on m-oriented sapphire were investigated by secondary ion mass spectrometry (SIMS) and scanning electron microscopy (SEM) in cathodoluminescence (CL) and energy dispersive X-ray modes. The deformation of the crystallographic structure of SLs was observed after rapid thermal annealing at 900{\deg}C in oxygen flow due to migration and segregation of Cd atoms. SIMS measurements revealed that the distributions of cadmium in the annealed samples depend on the thicknesses of the CdO and ZnO sublayers in the as grown superlattice structures. Depth-resolved CL measurements showed that shifting of the near band edge emission peaks is closely related to the Cd profiles measured with SIMS.