Linear piezoelectricity material constants for ammonothermal gallium nitride measured by bulk acoustic waves

Measurements of linear elastic and piezoelectric constants of gallium nitride by bulk acoustic waves are reported. All material properties, including static dielectric constants by capacitance method and density by x-ray method, were determined, using semi-insulating ammonothermally grown w-GaN. The obtained values: c(11) = 366.9 +/- 0.4 GPa, c(12) = 135.0 +/- 0.6 GPa, c(13) = 97.5 +/- 0.2 GPa, c(33) = 398.1 +/- 0.6 GPa, c(44) = 99.1 +/- 0.2 GPa, e(15) = -0.36 +/- 0.03 C m(-2), e(31) = -0.41 +/- 0.04 C m(-2), e(33) = 0.86 +/- 0.04 C m(-2), epsilon(1) = (9.3 +/- 0.3) epsilon(0), and epsilon(3) = (10.3 +/- 0.3) epsilon(0) are proposed as the new standard, confirming only some results from the very sparse and ambiguous published data.