On the Dynamic RON, Vertical Leakage and Capacitance Behavior in pGaN HEMTs With Heavily Carbon-Doped Buffers

In this letter, we investigate the effect of Carbon (C) doping concentration on dynamic RON, vertical leakage and Capacitance-Voltage (C-V) characteristics of p-GaN gate High Electron Mobility Transistors (HEMTs). Measurements performed on state-of-the-art samples show that further increasing C-doping concentration in the GaN buffer above 1019 cm−3 yields a reduced dynamic-RON degradation, in contrast with the behavior reported in the literature for lower C-doping concentrations. This is confirmed by a complete data set showing a consistent increase in the vertical leakage and in the output capacitance while increasing the C doping, stemming from a less insulating buffer and a reduced 2-DEG depletion, respectively. These observations can be attributed to an increased incorporation of compensating donors leading to a reduction of the net acceptors as the C doping concentration is raised above 1019 cm−3 .