Acoustic wave transduction in gallium nitride heterostructures

This paper highlights development efforts in the use of AlGaN/GaN heterostructures for launching, receiving and amplifying surface acoustic waves. High-electron mobility transistors (HEMTs) are demonstrated in acoustic wave delay lines with conventional interdigital transducers (IDTs). The amplitude for the transmitted Rayleigh mode is modulated through appropriate HEMT biasing conditions for a common source configuration. Modifying carrier density in the two-dimensional electron gas (2DEG) generates dynamic screening of the piezoelectric field. This directly affects the generation and detection of surface acoustic waves. In addition, the interaction of carriers with the phonons at the 2DEG can generate amplification of the traveling acoustic wave.