RF operation in graded Al <i> _x </i> Ga _{1− <i>x</i>} N ( <i>x</i> = 0.65 to 0.82) channel transistors

Abstract

The first report is presented on the RF operation of AlGaN channel transistor with Al‐composition above 80%. The reported device is a polarisation‐graded field effect transistor (PolFET) featuring an ultra‐wide bandgap (UWBG) AlGaN channel with Al‐composition grading from 65 to 82%. Transistors with a gate length of 0.8 μm were fabricated, with a current density of 265 mA/mm, the highest observed for AlGaN channel transistor with Al‐composition above 80%, and f T / f MAX of 5.4/14.2 GHz. This demonstration of RF operation of polarisation‐graded transistor provides a direction for achieving ultra‐wide bandgap AlGaN based devices for high performance RF and power switching applications.