Comments on "Epitaxially grown GaN thin-film SAW filter with high velocity and low insertion loss"

In 2001, Lee et al. (see ibid., vol.48, no.5, p.524-9, May 2001) proposed the use of GaN layers as a suitable material for surface-acoustic wave devices. They calculated the electromechanical coupling factor (k/sup 2/) for this material to be (4.3/spl plusmn/0.3)%. We have repeated their experiments and report a significantly lower value of k/sup 2/=(0.066/spl plusmn/0.003)% for a film thickness of /spl sim/0.1 times the acoustic wavelength.