Chemically vapor deposited Eu3+:Y2O3 thin films as a material platform for quantum technologies

Abstract

Rare earth ions hosted in solids are good candidates for quantum technologies due to their chemical stability and optical and spin transitions exhibiting long coherence lifetimes. While bulk oxide crystals are usually the preferred host material, the development of a scalable silicon-compatible thin film platform would be desirable. In this paper, we report on the growth of Y2(1−x)Eu2xO3 thin films on silicon in the full range of Eu3+ concentration by direct liquid injection chemical vapor deposition (CVD). Our sub-micrometer polycrystalline films with a strong-(111) texture were grown for all compositions into the bixbyite cubic phase. The variation of growth rates with temperature and flow indicated that deposition occurred through a mass-transport controlled regime. Optical assessment of the Eu-doped thin films showed inhomogeneous linewidths as narrow as 50 GHz and fluorescence lifetimes of 1 ms for the lowest concentrations. Finally, a spectral hole was successfully burned in a 200 nm-thin film with a 2% Eu doping leading to a homogeneous linewidth of 11 MHz. These values are still below those reported for bulk single crystals indicating that additional decoherence mechanisms exist in such nanometric films, which might be alleviated by further improvement of the crystalline quality. Nevertheless, these results pave the way to the use of CVD-grown Eu:Y2O3 thin films as a platform for integrated quantum devices.

Controlling the interfacial reactions and environment of rare-earth ions in thin oxide films towards wafer-scalable quantum technologies

“…We found an inhomogeneous linewidth of 40 GHz for the asgrown 2 % Eu:Y 2 O 3 thin film which is consistent with a previous study of thin films 35 . This value remains broader than for high quality nanoparticles (10 GHz at 0.3 % Eu:Y 2 O 3 ) 15 .…”

“…More details about the growth process are presented in the Electronic Supplementary Information (ESI) Fig. S1 and in a previous work 35 . Multi-layered (doped or undoped) films, with thicknesses varying from a few tens of nm up to 2 µm, were produced in this study.…”

“…Currently, the main challenge in nanometer thin films is to preserve the extremely narrow optical and spin homogeneous linewidth related to long coherence properties of RE ions against the presence of surface defects and impurities. Recently we have assessed the potential of both Atomic Layer Deposited (ALD) 30 and Chemically Vapor Deposited (CVD) 31 Eu-doped Y 2 O 3 films and managed to successfully burn spectral holes with a 22 MHz linewidth in the CVD films. This is at the state-of-the-art for thin films but still an order of magnitude larger than in optimized nanoparticles 17,32 .…”

Optical spin-state polarization in a binuclear europium complex towards molecule-based coherent light-spin interfaces

“…The QIP utility of Eu(III)-doped ceramics, powders, crystals, and nanoparticles-featuring 5 D 0 → 7 F 0 transition-has been elucidated 2,[25][26][27][28] . However, it is difficult to tailor-make such systems with desirable optical properties by means of chemical and physical manipulations, limiting the utility of such materials for QIP applications.…”

Molecule-based coherent light-spin interfaces for quantum information processing – optical spin state polarization in a binuclear Europium complex

“…The QIP utility of Eu(III)-doped ceramics, powders, crystals, and nanoparticles-featuring 5 D0→ 7 F0 transition-has been elucidated 2,[25][26][27][28] . However, it is difficult to tailor-make such systems with desirable optical properties by means of chemical and physical manipulations, limiting the utility of such materials for QIP applications.…”