Table 1 Figures of merit for various thin-film piezoelectric material used in PMUTs

In-plane deflection force, piezoelectric charge in deformed PMUTs

|e_31,f | (C/m²)

8–12

14

24

14

1.05

1.6

1

8.5–14.4

Dielectric constant

ε_33,f

300–1300

200–300

308

250

10.5

12

10.9

445

Piezoelectric voltage in deformed PMUTs

|e_31,f |/ε₀ε₃₃* (GV/m)

0.7–1.8

5.3–7.9

8.8

6.3

11.3

15

10.3

2.2–3.6

Coupling coefficient for flexural wave

e_31,f²/ε₀ε₃₃* (GPa)

5.6–54.2

110–74

211

88

11.9

24

10.3

18.3–53

Out-of-plane piezoelectric force

d_33,f (pC/N)

60–130

–

–

–

3.9

–

5.9

–

Out-of-plane elastic constant

c₃₃ (GPa)

98

–

–

–

395

–

208

–

Dielectric loss angle

tan δ (@ 1 to 10 kHz, 10⁵ V/m)

0.01–0.03

–

–

–

0.003

–

0.01–0.1

–

Signal-to-noise ratio

|e_31,f |/(ε₀ε₃₃tan δ)^0.5 (Pa^0.5)*

4–8

–

–

–

20

–

3–10

–