Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Applied Physics

Observation of single optical site of Eu and Mg codoped GaN grown by NH3-source molecular beam epitaxy

Hiroto Sekiguchi, Masaru Sakai, Takuho Kamada, Keisuke Yamane, Hiroshi Okada, Akihiro Wakahara

Published May 2, 2019• 9 citations
Publisher

Abstract

Eu-doped GaN (GaN:Eu) is a promising solid-state material for quantum information devices owing to its ideal quantum levels. However, a decrease of Eu concentration and the unification of optical sites are required for these devices to access an Eu ion. In this article, the effect of Eu concentration on the optical properties of Mg-codoped GaN:Eu was evaluated. The photoluminescence intensity from Eu ions increased linearly with increasing Eu concentration up to 1 × 1019 cm−3, beyond which the intensity saturated. This resulted from the increase of the sharp luminescence line at 620.5 nm (site A), which has a large excitation cross section, with increasing Eu concentration in the range of low Eu concentrations; an excess Eu concentration leads to the formation of other types of optical sites with a low transfer efficiency or inactive sites. For a low Eu concentration of 3 × 1018 cm−3, all optical sites except a specific optical site corresponding to site A disappeared, and the unification of optical sites was suggested. This result is expected to be valuable to realize quantum information devices.

DOI
10.1063/1.5090893

Related papers

Epitaxial growth and optical properties of Er-doped CeO2 on Si(111)

Tomohiro Inaba, Takehiko Tawara, Hiroo Omi +2 more

Epitaxial growth of erbium-doped cerium oxide (Er:CeO2) is achieved on Si (111) substrates by the cooperative integration of Si and oxide molecular beam epitaxy (MBE) technologies. Lattice matching between CeO2 and Si provides an attractive opportunity to build dilutely doped Er-based optical devices on a Si chip. The CeO2 host crystal is optically transparent for the telecom C-band wavelength and has quite a small magnetic moment, which serves as a disturbance-free environment for the two-level system formed in the doped Er. After the systematic optimization of the growth conditions for stoichiometric Er:CeO2; i.e., (Er + Ce)/O = 1/2, we varied the Er concentration in a range of 1 ~4%. The doped Er showed well-defined optical transitions at the wavelength of 1.533 μm irrespective of the Er concentration. With decreasing Er concentration, enhancement of the luminescence intensity, narrowing of the spectral width, and an increase in the radiative lifetime were observed. The results suggest that CeO2 on Si is promising as a platform for the doped-Er-based optical devices and their quantum optics applications.

Optical Materials Express•Aug 24, 2018•18 citations

A Pathway to Er Sites in Si with Long Spin and Optical Coherence Times

Alexey Lyasota, Ian R. Berkman, Gabriele G. de Boo +9 more

Rare-earth ions in solid-state hosts exhibit low homogeneous broadening and long spin coherence at cryogenic temperatures thus making them a promising candidate for optical quantum memories [1], optical-microwave transducers [2] and single dopant-based devices such as single photon emitters operating at the telecommunication wavelengths [3]. Here, we present an overview of the spin and optical properties of Er ensembles in Si accessed via resonant photoluminescence excitation (PLE) spectroscopy [4]. Samples were positioned directly on top of tailor-fabricated superconducting single photon detectors, placed in a dilution refrigerator unit and resonantly excited using fiber optics. Our method provided high collection efficiency and allowed spectral measurements of low Er density samples. The observed Er PLE spectra were strongly affected by the presence of co-dopants such as O, B or P reflecting their influence on the formation of optically active Er sites and corresponding Er optical transition energies. Higher O densities resulted in especially rich PLE spectra suggesting that a variety of Er-O complexes formed due to O doping. Lowering the O concentration, we achieved PLE spectra dominated by a single Er site in P doped samples. Interestingly, the Er spin relaxation and optical coherence properties were barely affected by the employed co-dopants and mainly depended on the Er concentration. By lowering the Er concentration from relatively high (1018cm-3) to low densities (1016cm-3), we were able to increase Er spin lifetimes from ~0.1 s to ~30 s. Long spin relaxation times allowed us to identify PLE spectra of new Er sites in Si. In both concentration regimes, we observed sub-MHz transient spectral holes suggesting long optical coherence times. Furthermore, we observed sub-MHz spin transitions in both natural and isotopically purified Si and achieved spin coherence times above 1 ms in isotopically purified Si. Narrow optical linewidths and long transverse and longitudinal spin relaxation times show that Er in Si is an excellent candidate for future quantum information and communication applications.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 26, 2023•0 citations

Ultrathin Eu- and Er-Doped Y2O3 Films with Optimized Optical Properties for Quantum Technologies

Marion Scarafagio, Alexandre Tallaire, Klaas‐Jan Tielrooij +9 more

Atomic layer deposited (ALD) Y 2 O 3 thin films have been thoroughly investigated for optical or electronic applications. The coherent spectroscopy of lanthanide ions doped into this material has also recently attracted increasing interest in the field of quantum technologies for which they are considered promising candidates in quantum memories or as spin–photon interfaces. However, these most demanding applications require a deep control over the local positioning of the ions and their close environment in the crystalline matrix. This study focuses on the structural as well as optical properties of Eu 3+ and Er 3+ dopants in Y 2 O 3 using photoluminescence (PL), luminescence decay times, and inhomogeneous line width (Γ inh ) measurements within this particular context. While as-grown ALD films do not provide an ideal host for the emitters, we demonstrate that by optimizing the deposition conditions and using appropriate annealing post treatments narrow inhomogeneous lines can be obtained for the 7 F 0 ↔ 5 D 0 transition of Eu 3+ even for nanoscale films. Furthermore, about 1.5 ms lifetime has been measured for the infrared telecom transition of Er in ultrathin films (<10 nm), which is an order of magnitude higher than in nanoparticles of the same size. These results validate optimized rare-earth-doped ALD Y 2 O 3 films as a suitable platform for photonics applications where few-nanometer-thick films with well-localized emitters are mandatory. This approach provides the first building blocks toward the development of more complex devices for quantum sensing or hybrid structures coupled with other systems such as two-dimensional materials.

The Journal of Physical Chemistry C•May 3, 2019•44 citations

Tunable Solid-State Quantum Memory Using Rare-Earth-Ion-Doped Crystal, Nd3+:GaN

S. Rudin, BC Connelly, VS Malinovsky +2 more

Abstract : The research objective of this Directors Research Initiative was to work on developing solid-state quantum memory using cryogenically cooled rare-earth-ion-doped crystal, Nd3 :GaN. The samples were grown using the US Army Research Laboratorys molecular beam epitaxy (MBE) capabilities. The approach is based on the coherent transient interaction between light and the ions in a semiconductor. We investigated the energy level structure of the neodymium (Nd) ions embedded into the semiconductor crystal lattice, gallium nitride (GaN), and developed a quantum description of the 2- and 3-pulse photon echo effect. Epitaxial GaN:Nd was grown by plasma-assisted molecular beam epitaxy in a modular Gen II reactor using liquid gallium, solid Nd, and a nitrogen plasma. The photoluminescence (PL) spectrum from the lowest 4F3/2 multiplet to all 4I9/2 multiplets was measured by a free-space variable amplifier silicon diode. A demonstration of the coherence properties requires a high-quality sample with a narrow homogeneous broadening. For this reason, the PL linewidth was characterized for various growth conditions. The experiments were carried out to observe coherent effects, and various experimental setups are described. In parallel with experiments on the coherence properties of Nd3 :GaN, we also investigated the effect of a varying electric field on the Nd PL spectrum to provide a tunable memory. To vary the applied field, we designed and grew a series of Nd-doped GaN p-i-n structures, strain-balanced superlattice structures, and periodic unbalanced structures.

•Apr 1, 2017•0 citations

Photon emission enhancement of praseodymium ions implanted with GaN nanopillars

Shinichiro Sato, Manato Deki, Li, Shuo +4 more

Lanthanoid (Ln)-doped Gallium Nitride (GaN) have attracted attentions because of their high intensity luminescence and sharp room-temperature (RT) optical linewidth. These superior luminescent properties are quite attractive for the application of single photon source (SPS) which is a key technology for quantum computing, quantum sensing, and quantum key distribution. However, one of the challenges to realize Ln-doped GaN SPS is the long luminescent transition lifetime, resulting in the low photon counts insufficient to optically detect isolated single Ln ions. Confinement of luminescent centers into nanometersized regions is an effective method to enhance their photon emission and we here we show that confinement into GaN nanopillars enhances photon emission from implanted praseodymium (Pr) ions at RT.

•Feb 12, 2020•0 citations

Er–Yb codoped CaF2 thin films grown by molecular beam epitaxy

E. Daran, R. Legros, P.L. Pernas +1 more

Yb:Er: codoped CaF2 monocrystalline films have been grown by molecular beam epitaxy (MBE) using YbF3, ErF3, and CaF2 evaporation on CaF2 substrates. Luminescence and excitation of luminescence at 25 K are measured in order to investigate the role of Yb3+ codoping and the effect of the growth conditions during the MBE process on the incorporation of active rare-earth species in CaF2. It is found, from a comparison with earlier work on singly doped thin films, that the energies of the levels of Er3+ ions are not modified by the double doping, whereas mixed complex centers are formed. Growth conditions are found to be important controlling factors for the incorporation of Yb3+ as a sensitizer, and, consequently, for the transfer efficiency. From excitation and absorption spectra it is shown that the lowest component of the Er:4I11/2 manifold has an energy higher than that of Yb:2F5/2 and the consequences are discussed.

Journal of Applied Physics•Jan 15, 1997•7 citations
Eu-doped GaN (GaN:Eu) is a promising solid-state material for quantum information devices owing to its ideal quantum levels. However, a decrease of Eu concentration and the unification of optical sites are required for these devices to access an Eu ion. In this article, the effect of Eu concentration on the optical properties of Mg-codoped GaN:Eu was evaluated. The photoluminescence intensity from Eu ions increased linearly with increasing Eu concentration up to 1 × 1019 cm−3, beyond which the intensity saturated. This resulted from the increase of the sharp luminescence line at 620.5 nm (site A), which has a large excitation cross section, with increasing Eu concentration in the range of low Eu concentrations; an excess Eu concentration leads to the formation of other types of optical sites with a low transfer efficiency or inactive sites. For a low Eu concentration of 3 × 1018 cm−3, all optical sites except a specific optical site corresponding to site A disappeared, and the unification of optical sites was suggested. This result is expected to be valuable to realize quantum information devices.
Epitaxial growth of erbium-doped cerium oxide (Er:CeO2) is achieved on Si (111) substrates by the cooperative integration of Si and oxide molecular beam epitaxy (MBE) technologies. Lattice matching between CeO2 and Si provides an attractive opportunity to build dilutely doped Er-based optical devices on a Si chip. The CeO2 host crystal is optically transparent for the telecom C-band wavelength and has quite a small magnetic moment, which serves as a disturbance-free environment for the two-level system formed in the doped Er. After the systematic optimization of the growth conditions for stoichiometric Er:CeO2; i.e., (Er + Ce)/O = 1/2, we varied the Er concentration in a range of 1 ~4%. The doped Er showed well-defined optical transitions at the wavelength of 1.533 μm irrespective of the Er concentration. With decreasing Er concentration, enhancement of the luminescence intensity, narrowing of the spectral width, and an increase in the radiative lifetime were observed. The results suggest that CeO2 on Si is promising as a platform for the doped-Er-based optical devices and their quantum optics applications.
Rare-earth ions in solid-state hosts exhibit low homogeneous broadening and long spin coherence at cryogenic temperatures thus making them a promising candidate for optical quantum memories [1], optical-microwave transducers [2] and single dopant-based devices such as single photon emitters operating at the telecommunication wavelengths [3]. Here, we present an overview of the spin and optical properties of Er ensembles in Si accessed via resonant photoluminescence excitation (PLE) spectroscopy [4]. Samples were positioned directly on top of tailor-fabricated superconducting single photon detectors, placed in a dilution refrigerator unit and resonantly excited using fiber optics. Our method provided high collection efficiency and allowed spectral measurements of low Er density samples. The observed Er PLE spectra were strongly affected by the presence of co-dopants such as O, B or P reflecting their influence on the formation of optically active Er sites and corresponding Er optical transition energies. Higher O densities resulted in especially rich PLE spectra suggesting that a variety of Er-O complexes formed due to O doping. Lowering the O concentration, we achieved PLE spectra dominated by a single Er site in P doped samples. Interestingly, the Er spin relaxation and optical coherence properties were barely affected by the employed co-dopants and mainly depended on the Er concentration. By lowering the Er concentration from relatively high (1018cm-3) to low densities (1016cm-3), we were able to increase Er spin lifetimes from ~0.1 s to ~30 s. Long spin relaxation times allowed us to identify PLE spectra of new Er sites in Si. In both concentration regimes, we observed sub-MHz transient spectral holes suggesting long optical coherence times. Furthermore, we observed sub-MHz spin transitions in both natural and isotopically purified Si and achieved spin coherence times above 1 ms in isotopically purified Si. Narrow optical linewidths and long transverse and longitudinal spin relaxation times show that Er in Si is an excellent candidate for future quantum information and communication applications.
Atomic layer deposited (ALD) Y 2 O 3 thin films have been thoroughly investigated for optical or electronic applications. The coherent spectroscopy of lanthanide ions doped into this material has also recently attracted increasing interest in the field of quantum technologies for which they are considered promising candidates in quantum memories or as spin–photon interfaces. However, these most demanding applications require a deep control over the local positioning of the ions and their close environment in the crystalline matrix. This study focuses on the structural as well as optical properties of Eu 3+ and Er 3+ dopants in Y 2 O 3 using photoluminescence (PL), luminescence decay times, and inhomogeneous line width (Γ inh ) measurements within this particular context. While as-grown ALD films do not provide an ideal host for the emitters, we demonstrate that by optimizing the deposition conditions and using appropriate annealing post treatments narrow inhomogeneous lines can be obtained for the 7 F 0 ↔ 5 D 0 transition of Eu 3+ even for nanoscale films. Furthermore, about 1.5 ms lifetime has been measured for the infrared telecom transition of Er in ultrathin films (<10 nm), which is an order of magnitude higher than in nanoparticles of the same size. These results validate optimized rare-earth-doped ALD Y 2 O 3 films as a suitable platform for photonics applications where few-nanometer-thick films with well-localized emitters are mandatory. This approach provides the first building blocks toward the development of more complex devices for quantum sensing or hybrid structures coupled with other systems such as two-dimensional materials.
Abstract : The research objective of this Directors Research Initiative was to work on developing solid-state quantum memory using cryogenically cooled rare-earth-ion-doped crystal, Nd3 :GaN. The samples were grown using the US Army Research Laboratorys molecular beam epitaxy (MBE) capabilities. The approach is based on the coherent transient interaction between light and the ions in a semiconductor. We investigated the energy level structure of the neodymium (Nd) ions embedded into the semiconductor crystal lattice, gallium nitride (GaN), and developed a quantum description of the 2- and 3-pulse photon echo effect. Epitaxial GaN:Nd was grown by plasma-assisted molecular beam epitaxy in a modular Gen II reactor using liquid gallium, solid Nd, and a nitrogen plasma. The photoluminescence (PL) spectrum from the lowest 4F3/2 multiplet to all 4I9/2 multiplets was measured by a free-space variable amplifier silicon diode. A demonstration of the coherence properties requires a high-quality sample with a narrow homogeneous broadening. For this reason, the PL linewidth was characterized for various growth conditions. The experiments were carried out to observe coherent effects, and various experimental setups are described. In parallel with experiments on the coherence properties of Nd3 :GaN, we also investigated the effect of a varying electric field on the Nd PL spectrum to provide a tunable memory. To vary the applied field, we designed and grew a series of Nd-doped GaN p-i-n structures, strain-balanced superlattice structures, and periodic unbalanced structures.
Lanthanoid (Ln)-doped Gallium Nitride (GaN) have attracted attentions because of their high intensity luminescence and sharp room-temperature (RT) optical linewidth. These superior luminescent properties are quite attractive for the application of single photon source (SPS) which is a key technology for quantum computing, quantum sensing, and quantum key distribution. However, one of the challenges to realize Ln-doped GaN SPS is the long luminescent transition lifetime, resulting in the low photon counts insufficient to optically detect isolated single Ln ions. Confinement of luminescent centers into nanometersized regions is an effective method to enhance their photon emission and we here we show that confinement into GaN nanopillars enhances photon emission from implanted praseodymium (Pr) ions at RT.
Yb:Er: codoped CaF2 monocrystalline films have been grown by molecular beam epitaxy (MBE) using YbF3, ErF3, and CaF2 evaporation on CaF2 substrates. Luminescence and excitation of luminescence at 25 K are measured in order to investigate the role of Yb3+ codoping and the effect of the growth conditions during the MBE process on the incorporation of active rare-earth species in CaF2. It is found, from a comparison with earlier work on singly doped thin films, that the energies of the levels of Er3+ ions are not modified by the double doping, whereas mixed complex centers are formed. Growth conditions are found to be important controlling factors for the incorporation of Yb3+ as a sensitizer, and, consequently, for the transfer efficiency. From excitation and absorption spectra it is shown that the lowest component of the Er:4I11/2 manifold has an energy higher than that of Yb:2F5/2 and the consequences are discussed.