Twin Domains in 111 oriented {CdO/MgO} superlattices: homoepitaxy versus heteroepitaxy

TL;DR

This study investigates the formation of twin domains in (111)-oriented CdO/MgO superlattices grown on different substrates, revealing how substrate symmetry influences domain structure during homoepitaxy and heteroepitaxy.

Contribution

It provides new insights into how substrate and epilayer symmetry relationships affect twin domain formation in (111)-oriented superlattices.

Findings

Superlattice on c-sapphire shows misoriented domains.

Superlattice on MgO substrate has no such domains.

Twin domains are rotated by 180° and 30° relative to each other and substrate.

Abstract

The structural properties of (111)-oriented {CdO/MgO} superlattice structures grown on c-sapphire and cubic MgO substrates have been studied by high resolution X-ray diffraction. The growth was performed in a plasma-assisted molecular beam epitaxy system. Although both superlattices are (111)-oriented and the {CdO/MgO} structure has 3m symmetry. It was shown that the superlattice on c-sapphire consists of misoriented domains, whereas no such domains were observed on (111) MgO. The twin domains are rotated by 180{\deg} with respect to each other and by 30{\deg} with respect to the sapphire substrate. We show that the crucial phenomena based on the formation of rotation domains and their number in heteroepitaxy depend fundamentally on the relationship between substrate and epilayer symmetries.