A surface acoustic wave (SAW) device includes a first interdigital transducer (IDT) and a second IDT each including interdigital electrodes disposed on a first surface of a substrate of piezoelectric material. The SAW device includes a diamond bridge enclosing an air cavity over a wave propagation region on the first surface of the substrate. The diamond bridge has a reduced height and provides improved thermal conductivity to avoid a reduction in performance and/or life span caused by heat generated in the SAW device. A process of fabricating a SAW device includes forming the first IDT and the second IDT in a metal layer on a first surface of a substrate comprising a piezoelectric material, the first IDT and the second IDT disposed in a wave propagation region of the first surface of the substrate, and forming a diamond bridge disposed above the wave propagation region.