Electromechanical coupling coefficient for surface acoustic waves in single-crystal bulk aluminum nitride

The electromechanical coupling coefficient K-2 for surface acoustic waves propagating on c and a surfaces of bulk AlN single crystals has been measured using the S-11-parameter method in the frequency range of 160-360 MHz. The extracted values of K-2 are 0.11% and 0.47% for the c and a surfaces, respectively. By fitting our experimental data to our numerical simulation results, we have estimated piezoelectric constants, which are in a reasonable agreement with literature data. Our results are consistent with the negative sign of the e(15) constant. (C) 2004 American Institute of Physics.