Scalable E-mode N-polar GaN MISFET devices and process with self-aligned source/drain regrowth

Abstract

E-mode GaN FETs fabricated on N-polar GaN have several unique scaling advantages such as vertical scaling of channel with back barrier for better electron confinement and regrowth of the n+ source/drain regions for reduced access resistance. They can also be integrated with recently demonstrated high performance N-polar D-mode [1] devices enabling novel circuit functionalities. Ga-polar E-mode devices with good performance have been demonstrated [2]; however in these devices source/drain contacts are invariably made to wideband gap AlxGa1−xN barriers leading to higher contact resistances which considerably limit the aggressive scaling of the device. Here we report E-mode N-polar GaN FETs fabricated with a scalable gate first process with self-aligned regrown source/drain regions and non-alloyed ohmic contacts for low access resistances. These devices show a peak drive current (Id) of 0.74 A/mm and peak transconductance (gm) of 250 mS/mm at Lg = 0.55 µm with a threshold voltage (Vth) of 0.8 V.