Site-dependent properties of quantum emitters in nanostructured silicon carbide

TL;DR

This study uses density functional theory to show how the properties of silicon vacancy defects in silicon carbide nanostructures depend on their specific site location, surface interactions, and structural changes, affecting their quantum applications.

Contribution

It reveals the site-dependent optical and electronic properties of silicon vacancies in SiC nanowires, highlighting the importance of finite-size effects and surface interactions.

Findings

Defect properties vary significantly with defect site and surface proximity.

Surface hybridization influences defect optical properties.

Charge-state stability is affected by surface migration and structural changes.

Abstract

Deep defects in silicon carbide (SiC) possess atom-like electronic, spin and optical properties, making them ideal for quantum-computing and -sensing applications. In these applications, deep defects are often placed within fabricated nanostructures that modify defect properties due to surface and quantum confinement effects. Thus far, theoretical studies exploring deep defects in SiC have ignored these effects. Using density functional theory, this work demonstrates site-dependence of properties of bright, negatively-charged silicon monovacancies within a SiC nanowire. It is shown that the optical properties of defects depend strongly on the hybridization of the defect states with the surface states and on the structural changes allowed by proximity to the surfaces. Additionally, the analysis of the first principles results indicates that the charge-state conversion and/or migration to thermodynamically-favorable undercoordinated surface sites can deteriorate deep-defect properties. These results illustrate the importance of considering how finite-size effects tune defect properties, and of creating mitigating protocols to ensure a defect's charge-state stability within nanostructured hosts.