High transconductance heterostructure field-effect transistors based on AlGaN/GaN

We report on the fabrication and characterization of Al0.15Ga0.85N/GaN heterostructure field-effect transistors (HFETs) with transconductance as high as 120 mS/mm and saturated current density of 0.35 A/mm for a device with a gate length and width of 1 and 100 mu m. This represents one of the best results for such device. A comparison of the maximum transconductance of devices on wafers with different channel conductance is presented to analyze the factors limiting the performance. Our data indicates the series resistance between the source and drain to be the limiting factor for the maximum de transconductance. (C) 1996 American Institute of Physics.