Assessing the effects of field plates in an AlGaN/GaN-on-SiC HEMT model extraction

The contributions of gate-connected and source-connected field plates to extracted device capacitances (gate-source, gate-drain and drain-source capacitance) are assessed during the development of an AlGaN/GaN-on-SiC HEMT model. The capacitances due to the presence of a gate field plate are observed to be intrinsic in nature, while those associated with a source-connected field plate can be regarded as extrinsic. Close agreement is observed between measurement and simulation of S-parameters using a device model which considers the individual effects of the field plates.