Berlin 2005 – wissenschaftliches Programm
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AK: Akustik
AK 2: Hochfrequenzakustik - akustische Oberfl
ächenwellen (Sitzungsorganisation: Eduard Chilla, Teltow)
AK 2.2: Vortrag
Freitag, 4. März 2005, 14:45–15:00, TU EB222
Confinement of surface acoustic waves in AlN/GaN/γ-LiAlO2 acoustic wells — •Y. Takagaki1, E. Chilla2, and K. H. Ploog1 — 1Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany — 2Vectron International, Tele Filter GmbH, Potsdamer Str. 18, D-14513 Teltow, Germany
We numerically investigate the characteristics of surface acoustic waves (SAWs) in AlN/GaN/γ-LiAlO2 heterostructures. The large difference of the sound velocities in AlN and GaN leads to an expulsion of SAWs from the top AlN layer and their resultant relocation to the middle GaN layer in the short wavelength regime. The SAW velocity in the limit of zero wavelength is given by a bulk sound velocity of GaN, owing to the capping by the AlN barrier layer. The extra confinement of the SAW power in the acoustic well is advantageous in manipulating the operation of GaN-based devices by SAWs. The threshold velocity for the appearance of guided Rayleigh-like modes is found to be smaller than the bulk transverse sound velocity in the substrate. The present system provides furthermore unusual behaviour of SAWs.