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End date: 2024 × Start date: 2020 × Publisher: Melville, NY : American Inst. of Physics × Subject: Gallium compounds ×

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    High-temperature electromechanical loss in piezoelectric langasite and catangasite crystals
    (Melville, NY : American Inst. of Physics, 2021) Suhak, Yuriy; Fritze, Holger; Sotnikov, Andrei; Schmidt, Hagen; Johnson, Ward L.
    Temperature-dependent acoustic loss Q−1 is studied in partially disordered langasite (LGS, La3Ga5SiO14) and ordered catangasite (CTGS, Ca3TaGa3Si2O14) crystals and compared with previously reported CTGS and langatate (LGT, La3Ga5.5Ta0.5O14) data. Two independent techniques, a contactless tone-burst excitation technique and contacting resonant piezoelectric spectroscopy, are used in this study. Contributions to the measured Q−1(T) are determined through fitting to physics-based functions, and the extracted fit parameters, including the activation energies of the processes, are discussed. It is shown that losses in LGS and CTGS are caused by a superposition of several mechanisms, including intrinsic phonon–phonon loss, point-defect relaxations, and conductivity-related relaxations.
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    Suppression of particle formation by gas-phase pre-reactions in (100) MOVPE-grown β -Ga2O3films for vertical device application
    (Melville, NY : American Inst. of Physics, 2023) Chou, Ta-Shun; Seyidov, Palvan; Bin Anooz, Saud; Grüneberg, Raimund; Pietsch, Mike; Rehm, Jana; Tran, Thi Thuy Vi; Tetzner, Kornelius; Galazka, Zbigniew; Albrecht, Martin; Irmscher, Klaus; Fiedler, Andreas; Popp, Andreas
    This work investigated the metalorganic vapor-phase epitaxy (MOVPE) of (100) β-Ga2O3 films with the aim of meeting the requirements to act as drift layers for high-power electronic devices. A height-adjustable showerhead achieving a close distance to the susceptor (1.5 cm) was demonstrated to be a critical factor in increasing the stability of the Ga wetting layer (or Ga adlayer) on the surface and reducing parasitic particles. A film thickness of up to 3 μm has been achieved while keeping the root mean square below 0.7 nm. Record carrier mobilities of 155 cm2 V-1 s-1 (2.2 μm) and 163 cm2 V-1 s-1 (3 μm) at room temperature were measured for (100) β-Ga2O3 films with carrier concentrations of 5.7 × 1016 and 7.1 × 1016 cm-3, respectively. Analysis of temperature-dependent Hall mobility and carrier concentration data revealed a low background compensating acceptor concentration of 4 × 1015 cm-3.