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.
Highlights
Quantum technologies (QT) are witnessing an increasing interest with the promise to offer new systems and devices with unrivalled performance: ultra-sensitive sensors, quantum computers, information processing, highly-secured communication networks etc[1]
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 Vapour Deposition
High structural order was achieved for deposition temperatures in the range 650-1050 °C which corresponds to a mass-transport dominated regime
Summary
Quantum technologies (QT) are witnessing an increasing interest with the promise to offer new systems and devices with unrivalled performance: ultra-sensitive sensors, quantum computers, information processing, highly-secured communication networks etc[1]. Rare-earth ions (REI) are outstanding as they exhibit extremely narrow optical homogeneous linewidths at low temperature, in the range of a few kHz to less than 100 Hz in bulk single crystals[2]. We have shown that optical homogeneous linewidths as narrow as 30 kHz14 can be obtained in specially prepared yttrium oxide (Y2O3) nanocrystals doped with Eu3+ ions, the lowest ever measured for nanoscale solids[15,16] While this value remains above that of bulk crystals, integration of these nanoparticles into an optical fibre cavity could be successfully obtained[10]. Further details on the SHB setup used and the procedure are given in the supplementary information file (Fig. S5)
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