A Thickness-Mode AlGaN/GaN Resonant Body High Electron Mobility Transistor

A multigigahertz AlGaN/GaN resonant body transistor (RBT) is reported, wherein the mechanical resonance and electrical signal modulation are achieved simultaneously. A 175-Å-thick AlGaN layer is used as the piezoelectric transduction layer, and the 2-D electron gas present at the AlGaN/GaN interface is employed as the bottom electrode as well as the transistor conducting channel. The carrier concentration of the channel is modulated when the device undergoes acoustic strain. A quality factor of 250 and acoustic transconductance of 25
$\mu{\rm S}$
is achieved at resonance frequency of 4.23 GHz, marking the highest frequency and highest transconductance reported to date for GaN-based RBTs. The
${\rm frequency}\times Q$
of this device is among the best reported for GaN-based resonators.