Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 40: Thermal, acoustic and transport properties
HL 40.9: Talk
Wednesday, March 18, 2020, 12:00–12:15, POT 151
Generation and propagation of superhigh-frequency bulk acoustic waves in GaAs — Diego H. O. Machado1, 2, •Antonio Crespo-Poveda1, Alexander S. Kuznetsov1, Klaus Biermann1, Luis V. A. Scalvi2, and Paulo V. Santos1 — 1Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany — 2UNESP, Department of Physics, 17033-360 Bauru (SP), Brazil
Coherent superhigh-frequency (SHF) vibrations provide an excellent tool for the modulation and control of excitations in semiconductors. Here, we investigate the piezoelectric generation and propagation of longitudinal bulk acoustic waves (LBAWs) with frequencies up to 20 GHz in GaAs crystals using monolithic bulk acoustic-wave resonators based on piezoelectric thin ZnO films. The transducers are used to investigate the propagation of the LBAWs in the frequency and temperature ranges from 1 to 20 GHz and 10 and 300 K, respectively. We find that the acoustic absorption of GaAs in the temperature range from 80 K to 300 K is dominated by scattering with thermal phonons. In contrast, at lower temperatures, the acoustic absorption saturates at a frequency-dependent value. Experiments carried out with different propagation lengths indicate that the saturation is associated with losses during reflections at the sample boundaries. We also demonstrate devices with a high quality factor fabricated on top of acoustic Bragg reflectors. These findings prove the feasibility of high-quality acoustic resonators embedding GaAs-based nanostructures, opening exciting new technological opportunities, such as acoustic carrier control and nanomechanics in the SHF range.