A simulation study of enhancement-mode AlGaN/GaN HEMTs with recessed gates

The properties of GaN and AlN and their heterostructures have encouraged the research of AlGaN/GaN based transistors for various applications in the last decade. Consequently, outstanding results have been reported for depletion-mode high electron mobility transistors (DHEMT) in recent years. However, for several applications (both analog and digital) enhancement-mode devices (EHEMT) are essential. There are few approaches for attaining normally-off characteristics. In this work, we analyze the trade-off between high frequency performance and threshold voltage achieved by gate recess technique. Results from two-dimensional hydrodynamic simulations, supported by experimental data, are presented.