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Subject: Optical properties × WGL Institute: IKZ ×

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Now showing 1 - 2 of 2
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    Anisotropic optical properties of highly doped rutile SnO2: Valence band contributions to the Burstein-Moss shift
    (New York : American Institute of Physics, 2018) Feneberg, Martin; Lidig, Christian; White, Mark E.; Tsai, Min Y.; Speck, James S.; Bierwagen, Oliver; Galazka, Zbigniew; Goldhahn, Rüdiger
    The interband absorption of the transparent conducting semiconductor rutile stannic oxide (SnO2) is investigated as a function of increasing free electron concentration. The anisotropic dielectric functions of SnO2:Sb are determined by spectroscopic ellipsometry. The onsets of strong interband absorption found at different positions shift to higher photon energies with increasing free carrier concentration. For the electric field vector parallel to the optic axis, a low energy shoulder increases in prominence with increasing free electron concentration. We analyze the influence of different many-body effects and can model the behavior by taking into account bandgap renormalization and the Burstein-Moss effect. The latter consists of contributions from the conduction and the valence bands which can be distinguished because the nonparabolic conduction band dispersion of SnO2 is known already with high accuracy. The possible originsof the shoulder are discussed. The most likely mechanism is identified to be interband transitions at jkj > 0 from a dipole forbidden valence band.
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    A photonic platform for donor spin qubits in silicon
    (Washington, DC [u.a.] : Assoc., 2017) Morse, Kevin J.; Abraham, Rohan J. S.; DeAbreu, Adam; Bowness, Camille; Richards, Timothy S.; Riemann, Helge; Abrosimov, Nikolay V.; Becker, Peter; Pohl, Hans-Joachim; Thewalt, Michael L. W.; Simmons, Stephanie
    Donor spins in silicon are highly competitive qubits for upcoming quantum technologies, offering complementary metal-oxide semiconductor compatibility, coherence (T2) times of minutes to hours, and simultaneous initialization, manipulation, and readout fidelities near ~99.9%. This allows for many quantum error correction protocols, which will be essential for scale-up. However, a proven method of reliably coupling spatially separated donor qubits has yet to be identified. We present a scalable silicon-based platform using the unique optical properties of “deep” chalcogen donors. For the prototypical 77Se+ donor, we measure lower bounds on the transition dipole moment and excited-state lifetime, enabling access to the strong coupling limit of cavity quantum electrodynamics using known silicon photonic resonator technology and integrated silicon photonics. We also report relatively strong photon emission from this same transition. These results unlock clear pathways for silicon-based quantum computing, spin-to-photon conversion, photonic memories, integrated single-photon sources, and all-optical switches.