Electromechanical coupling and gigahertz elastic properties of ScAlN films near phase boundary

Abstract

The electromechanical coupling, elastic properties, and temperature coefficient of elastic constant c33D of ScxAl(1−x)N films with high Sc concentration (x) of 0–0.70 were experimentally investigated. Near the phase boundary, a Sc0.41Al0.59N film exhibited a maximum thickness extensional mode electromechanical coupling coefficient kt2 of 12% (kt = 0.35), which is almost double the value of 6.4% for typical pure AlN films. In the region of 0 < x < 0.2, the electromechanical coupling was confirmed to increase without any detectable deterioration in the temperature stability of c33D (=−54.5 ppm/ °C). This region is favorable in terms of temperature stability and is suitable for wideband resonator filter applications.

Effect of Sc concentration on shear wave velocities in ScAlN films measured by micro-Brillouin scattering technique

“…The previously investigated longitudinal wave velocities (c 33 D /ρ) 1/2 are also plotted in Fig. 9(b) [9]. The wave velocities [(c 66 /ρ) 1/2 , (c 11 /ρ) 1/2 and (c 33 D /ρ) 1/2 ] with the Sc concentration of 40% reported by Tanaka's group in IUS 2014 are also plotted in Fig.…”

“…:(c 33 D /ρ) 1/2 (Ultrasonic microscopy [14]) [9]. The wave velocities [(c66/ρ) 1/2 , (c11/ρ) 1/2 and (c33 D /ρ) 1/2 ] in ScAlN with Sc concentration of 40% reported by Tanaka's group are plotted in both graphs (a) and (b) [14].…”

“…Matloub et al investigated the longitudinal wave velocity (c 33 D /ρ) 1/2 in a ScAlN FBAR with Sc concentration of 12 %, and showed that the velocity (10300 m/s) was lower than that of a single crystalline AlN (11132 m/s) [6,8]. Our group previously investigated the longitudinal wave velocities v = (c 33 D /ρ) 1/2 in ScAlN films with high Sc concentrations of 0-63% [9]. These acoustic wave velocities were determined from the longitudinal wave conversion losses of high-overtone bulk acoustic resonators (HBARs).…”

Band alignment at AlN/Si (111) and (001) interfaces

“…7,8 Accordingly, there is significant interest in AlN and AlN/ III-N alloys for numerous electronic, 9,10 opto-electronic, 11,12 electro-mechanical, 13,14 electro-acoustic, 15,16 and energy harvesting 17,18 device applications. Due to inherent economic advantages, significant interest exists for fabricating these and related AlN based devices on large diameter silicon (Si) substrates.…”

Rapid and simultaneous measurement of longitudinal and shear wave velocities by Brillouin scattering from artificially induced phonons

“…Here, the RI8A scattering geometry in Fig. 3 was used [13]. This geometry was attained by attaching a flat metal film to the rear surface of the samples as a reflector, and enabled the simultaneous measurement of longitudinal and shear phonons that propagate in both wave-vectors of lyA and qlSO.…”