High performance GaN high electron mobility transistors on low resistivity silicon for X -Band Applications

This letter reports the RF performance of a 0.3-μm gate length AlGaN/AlN/GaN HEMT realized on a 150-mm diameter low-resistivity (LR) (σ < 10 � · cm) silicon substrate. Short circuit current gain ( fT ) and maximum frequency of oscillation ( fMAX) of 55 and 121 GHz, respectively, were obtained. To our knowledge, these are the highest fT / fMAX values reported to date for GaN HEMTs on LR silicon substrates