Bias dependence of the access resistance in GaN HEMTs

Based on TCAD simulations and s-parameter measurement of GaN HEMTs, it is shown that the source and drain resistance are bias dependent, even though gate-forward resistance extraction still yields a constant value. If the extrinsic resistance variation is ignored in parameter extraction, the inaccuracy is consumed by the transconductance, while s-parameter prediction still agrees with the measurements.