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Author: Trampert, Achim × Subject: Thin films ×

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    Epitaxial synthesis of unintentionally doped p-type SnO (001) via suboxide molecular beam epitaxy
    (Melville, NY : AIP, 2023) Egbo, Kingsley; Luna, Esperanza; Lähnemann, Jonas; Hoffmann, Georg; Trampert, Achim; Grümbel, Jona; Kluth, Elias; Feneberg, Martin; Goldhahn, Rüdiger; Bierwagen, Oliver
    By employing a mixed SnO2 + Sn source, we demonstrate suboxide molecular beam epitaxy (S-MBE) growth of phase-pure single-crystalline metastable SnO (001) thin films on Y-stabilized ZrO2 (001) substrates at a growth rate of ∼1.0 nm/min without the need for additional oxygen. These films grow epitaxially across a wide substrate temperature range from 150 to 450 °C. Hence, we present an alternative pathway to overcome the limitations of high Sn or SnO2 cell temperatures and narrow growth windows encountered in previous MBE growth of metastable SnO. In situ laser reflectometry and line-of-sight quadrupole mass spectrometry were used to investigate the rate of SnO desorption as a function of substrate temperature. While SnO ad-molecule desorption at TS = 450 °C was growth-rate limiting, the SnO films did not desorb at this temperature after growth in vacuum. The SnO (001) thin films are transparent and unintentionally p-type doped, with hole concentrations and mobilities in the range of 0.9-6.0 × 1018 cm-3 and 2.0-5.5 cm2 V-1 s-1, respectively. These p-type SnO films obtained at low substrate temperatures are promising for back-end-of-line (BEOL) compatible applications and for integration with n-type oxides in pn heterojunctions and field-effect transistors.
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    Fano-like resonances sustained by Si doped InAsSb plasmonic resonators integrated in GaSb matrix
    (Washington, DC : Optical Society of America, 2015) Taliercio, Thierry; Guilengui, Vilianne NTsame; Cerutti, Laurent; Rodriguez, Jean-Baptiste; Barho, Franziska; Rodrigo, Maria-José Milla; Gonzalez-Posada, Fernando; Tournié, Eric; Niehle, Michael; Trampert, Achim
    By using metal-free plasmonics, we report on the excitation of Fano-like resonances in the mid-infrared where the Fano asymmetric parameter, q, varies when the dielectric environment of the plasmonic resonator changes. We use silicon doped InAsSb alloy deposited by molecular beam epitaxy on GaSb substrate to realize the plasmonic resonators exclusively based on semiconductors. We first demonstrate the possibility to realize high quality samples of embedded InAsSb plasmonic resonators into GaSb host using regrowth technique. The high crystalline quality of the deposited structure is confirmed by scanning transmission electron microscopy (STEM) observation. Second, we report Fano-like resonances associated to localized surface plasmons in both cases: uncovered and covered plasmonic resonators, demonstrating a strong line shape modification. The optical properties of the embedded structures correspond to those modeled by finite-difference time-domain (FDTD) method and by a model based on Fano-like line shape. Our results show that all-semiconductor plasmonics gives the opportunity to build new plasmonic structures with embedded resonators of highly doped semiconductor in a matrix of un-doped semiconductor for mid-IR applications.