Controlled Growth of Rare-Earth-Doped TiO 2 Thin Films on III–V Semiconductors for Hybrid Quantum Photonic Interfaces

Henry C. Hammer; Caleb Whittier; Nathan A. Helvy; Christopher Rouleau; Nabil D. Bassim; Ravitej Uppu

doi:10.1021/acsaom.5c00585

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Controlled Growth of Rare-Earth-Doped TiO 2 Thin Films on III–V Semiconductors for Hybrid Quantum Photonic Interfaces

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Controlled Growth of Rare-Earth-Doped TiO 2 Thin Films on III–V Semiconductors for Hybrid Quantum Photonic Interfaces

Henry C. Hammer, Caleb Whittier, Nathan A. Helvy, Christopher Rouleau, Nabil D. Bassim and Ravitej Uppu

ACS applied optical materials, Vol.4(2), pp.457-470

02/04/2026

DOI: 10.1021/acsaom.5c00585

PMCID: PMC12954842

PMID: 41783648

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Abstract

Quantum photonic networks require two distinct functionalities: bright single-photon sources and long-lived quantum memories. III–V semiconductor quantum dots (QDs) excel as deterministic and coherent photon emitters, while rare-earth ions such as erbium (Er3+) in crystalline oxides offer exceptional spin and optical coherence at telecom wavelengths. Combining these systems and their functionalities via direct epitaxy is challenging due to lattice mismatch and incompatible growth conditions. Here, we demonstrate the low-temperature pulsed laser deposition of Er3+-doped TiO2 thin films directly on GaAs and GaSb substrates. Controlled surface preparation with an arsenic cap and an oxygen-deficient buffer layer enables the growth of epitaxial anatase TiO2 (001) at ∼390 °C with sub-300 pm surface roughness, while avoiding interface degradation. In contrast, high-temperature oxide desorption or growth temperatures drive the transition to a rough, polycrystalline rutile film, as confirmed by transmission electron microscopy. Minimal coincident interface area (MCIA) modeling explains the orientation-selective growth on GaAs and GaSb. Raman and cryogenic photoluminescence excitation spectroscopy verify the crystal phase and optical activation of Er3+ ions. This multiparameter growth strategy helps preserve III–V quantum dot functionality and yields smooth surfaces suitable for low-loss nanophotonic structures. Our results establish a materials platform for monolithically integrating rare-earth quantum memories with semiconductor photon sources, paving the way toward scalable hybrid quantum photonic chips.

rare-earth spins

opticalcoherence

quantumphotonics

quantum information

heteroepitaxy

Details

Title: Subtitle: Controlled Growth of Rare-Earth-Doped TiO 2 Thin Films on III–V Semiconductors for Hybrid Quantum Photonic Interfaces
Creators: Henry C. Hammer - University of Iowa
Caleb Whittier - McMaster University
Nathan A. Helvy - University of Iowa
Christopher Rouleau - Oak Ridge National Laboratory
Nabil D. Bassim - McMaster University
Ravitej Uppu - University of Iowa
Resource Type: Journal article
Publication Details: ACS applied optical materials, Vol.4(2), pp.457-470
DOI: 10.1021/acsaom.5c00585
PMID: 41783648
PMCID: PMC12954842
NLM abbreviation: ACS Appl Opt Mater
ISSN: 2771-9855
eISSN: 2771-9855
Publisher: American Chemical Society
Grant note: Natural Sciences and Engineering Research Council of Canada: ALLRP 580935 22 U.S. Department of Energy: CNMS2023-B-02072 University of Iowa: NA National Science Foundation: ECCS2339469
This material is based upon work supported by the National Science Foundation under Award No. ECCS2339469. R.U. acknowledges a seed grant from the University of Iowa's Office of the Vice President for Research through the P3 Jumpstarting Tomorrow program. N.D.B. thanks the Natural Sciences and Engineering Research Council of Canada (NSERC) for financially supporting this work under the Alliance International Catalyst Quantum grants program (ALLRP 580935 - 22). The authors acknowledge support for carrying out the focused ion beam milling (FIB) and STEM work at the Canadian Centre for Electron Microscopy (CCEM), a national facility supported by McMaster University, the Ontario Research Fund (ORF), and the Canada Foundation for Innovation (CFI). Target fabrication, PLD, and a portion of the AFM and XRD research were conducted as part of a user project (CNMS2023-B-02072) at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The authors acknowledge the University of Iowa Materials Analysis, Testing, and Fabrication (MATFab) Facility for the use of XRD and Raman spectroscopy instrumentation. The authors thank Prof. John Prineas for arsenic-capped wafer growth at the University of Iowa's Molecular Beam Epitaxy facility.
Language: English
Date published: 02/04/2026
Academic Unit: Physics and Astronomy
Record Identifier: 9985139463402771

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