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arXiv · 2309.16644

Optical and microstructural characterization of Er$^{3+}$ doped epitaxial cerium oxide on silicon

Gregory D. Grant·Jiefei Zhang·Ignas Masiulionis·Swarnabha Chattaraj·Kathryn E. Sautter·Sean E. Sullivan·Rishi Chebrolu·Yuzi Liu·Jessica B. Martins·Jens Niklas·Alan M. Dibos·Sumit Kewalramani·John W. Freeland·Jianguo Wen·Oleg G. Poluektov·F. Joseph Heremans·David D. Awschalom·Supratik Guha
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Abstract

Rare-earth ion dopants in solid-state hosts are ideal candidates for quantum communication technologies such as quantum memory, due to the intrinsic spin-photon interface of the rare-earth ion combined with the integration methods available in the solid-state. Erbium-doped cerium oxide (Er:CeO$_2$) is a particularly promising platform for such a quantum memory, as it combines the telecom-wavelength (~1.5 $\mu$m) 4f-4f transition of erbium, a predicted long electron spin coherence time supported by CeO$_2$, and is also near lattice-matched to silicon for heteroepitaxial growth. In this work, we report on the epitaxial growth of Er:CeO$_2$ thin films on silicon using molecular beam epitaxy (MBE), with controlled erbium concentration down to 2 parts per million (ppm). We carry out a detailed microstructural study to verify the CeO$_2$ host structure, and characterize the spin and optical properties of the embedded Er$^{3+}$ ions. In the 2-3 ppm Er regime, we identify EPR linewidths of 245(1) MHz, optical inhomogeneous linewidths of 9.5(2) GHz, optical excited state lifetimes of 3.5(1) ms, and spectral diffusion-limited homogenoeus linewidths as narrow as 4.8(3) MHz in the as-grown material. We test annealing of the Er:CeO$_2$ films up to 900 deg C, which yields modest narrowing of the inhomogeneous linewidth by 20% and extension of the excited state lifetime by 40%. We have also studied the variation of the optical properties as a function of Er doping and find that the results are consistent with the trends expected from inter-dopant charge interactions.

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Gregory D. Grant, Jiefei Zhang, Ignas Masiulionis, Swarnabha Chattaraj, Kathryn E. Sautter, Sean E. Sullivan, Rishi Chebrolu, Yuzi Liu, Jessica B. Martins, Jens Niklas, Alan M. Dibos, Sumit Kewalramani, John W. Freeland, Jianguo Wen, Oleg G. Poluektov, F. Joseph Heremans, David D. Awschalom, Supratik Guha. 2023-09-28. Optical and microstructural characterization of Er$^{3+}$ doped epitaxial cerium oxide on silicon. https://arxiv.org/abs/2309.16644

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