A Compact Surface Potential Model for Flexible Radio Frequency AlGaN/GaN High-Electron-Mobility Transistor

Compact model of flexible radio frequency (RF) electronic devices is crucial for flexible circuit designs. In this article, a compact model, including external strain effects for flexible RF gallium nitride (GaN) high-electron-mobility transistor, is presented. First, the carrier density and threshold voltage with external mechanical uniaxial strain is analytically characterized by introducing the strained piezoelectric charge
$\Delta \sigma $
, Schottky barrier height
$\Delta \phi _{B}$
, and surface state density
$D_{\mathrm {it}}$
into the model. Then, the variations of the conduction band offset at the AlGaN/AlN and AlN/GaN interfaces are considered. Finally, the complete large-signal model is established after embedding strain effect into intrinsic drain current and nonlinear capacitance models. The proposed model is verified by measurements, including direct current
$I$
–
$V$
characteristics, small-signal
$S$
-parameters up to 40 GHz, and large-signal power performance—output power, efficiency, and gain. The proposed model will be useful for the RF application of flexible electronics.