Influence of shadowing effect on shear mode acoustic properties in the c-axis tilted AlN films

Author

Suzuki, Masashi ; Yanagitani, Takahiko

Author_Institution

Grad. Sch. of Eng., Nagoya Inst. of Technol., Nagoya, Japan

fYear

2010

fDate

11-14 Oct. 2010

Firstpage

1478

Lastpage

1481

Abstract

c-axis tilted AIN films have been studied for use in quasi-shear mode devices. Highly tilted columnar structure induces the decrease of film density (void between columnar grains) because of the shadowing effect. This could affect the performance of shear mode resonator. In this study, the relationship between the acoustic properties and the grain structure is investigated in c-axis tilted AIN film. Acoustic properties of the resonators were estimated by the characteristic of conversion loss in composite resonator. In c-axis highly tilted AIN film, 1/4 and 3/4 wavelength resonance due to the decrease of shear wave velocity were observed in a number of samples. This phenomenon was not observed in longitudinal wave mode. Porous film structure was also observed in the highly tilted films by across sectional SEM image. Decrease of shear wave velocity would be caused by this structure because shear wave is more sensitive to the porous structure than longitudinal wave.

Keywords

III-V semiconductors; acoustic resonators; acoustic waves; aluminium compounds; composite materials; crystal microstructure; porous semiconductors; scanning electron microscopy; semiconductor thin films; sputter deposition; tilt boundaries; wide band gap semiconductors; AlN; RF magnetron sputtering; SEM; c-axis tilted porous film structure; columnar grain structure; conversion loss; film density; quasishear mode composite resonators; scanning electron microscopy; shadowing effect; shear mode acoustic properties; shear wave velocity; wavelength resonance; Acoustics; Anodes; Crystals; Films; Propagation losses; Sputtering; Substrates; Acoustic properties; AlN; Shadowing effect; Sputtering deposition; c-axis tlted film;

fLanguage

English

Publisher

ieee

Conference_Titel

Ultrasonics Symposium (IUS), 2010 IEEE

Conference_Location

San Diego, CA

ISSN

1948-5719

Print_ISBN

978-1-4577-0382-9

Type

conf

DOI

10.1109/ULTSYM.2010.5935561

Filename

5935561