RF Performance of Trigate GaN HEMTs

The impact of the trigate GaN high electron mobility transistor (HEMT) body geometry on the device RF performance is investigated by 3-D numerical simulations. The trigate concept is a viable approach to achieve normally off operation and to suppress short-channel effects. The effect of gate length scaling on the RF behavior is studied and guidelines for design improvements are provided. Furthermore, it is shown that trigate HEMTs with improved body design and/or InAlN barriers causing a higher polarization charge than AlGaN can exhibit better RF figures of merit than planar GaN HEMTs.