The Role of the Dopant in the Electronic Structure of Erbium-Doped \ch{TiO2} for Quantum Emit

TL;DR

This study investigates how erbium doping affects the electronic and crystal structures of TiO2 films, revealing that defects and lattice distortions limit coherence times crucial for quantum technology applications.

Contribution

It provides detailed insights into the site occupancy and lattice distortions caused by erbium in TiO2, highlighting defect-related limitations on coherence times.

Findings

Erbium primarily occupies Ti sites in TiO2.

Doping causes lattice distortions and defects.

Coherence times are limited by defect-induced decay pathways.

Abstract

Erbium-doped \ch{TiO2} materials are promising candidates for advancing quantum technologies, necessitating a thorough understanding of their electronic and crystal structures to tailor their properties and enhance coherence times. This study explored epitaxial erbium-doped rutile \ch{TiO2} films deposited on r-sapphire substrates using molecular beam epitaxy. Photoluminescence excitation spectroscopy demonstrated decreasing fluorescence lifetimes with erbium doping, indicating limited coherence times. Lattice distortions associated with \ch{Er^{3+}} were probed by X-ray absorption spectroscopy, indicating that erbium primarily occupies \ch{Ti^{4+}} sites and influences oxygen vacancies. Significant lattice distortions in the higher-order shells and full coordination around erbium suggest that additional defects are likely prevalent in these regions. These findings indicate that defects contribute to limited coherence times by introducing alternative decay pathways, leading to shorter fluorescence lifetimes.