Small signal equivalent circuit model for III-nitride MODFET's with large ohmic contacts

초록

A small signal equivalent circuit model of III-nitride modulation-doped field-effect transistors (MODFET's) with large ohmic contact resistance is presented. Through subsequent strippings of Y-parasitics from pad capacitances and Z-parasitics from access reactances, we determined the intrinsic equivalent circuit model. Due to the high contact resistances of ohmic metals on III-V nitride materials, a special treatment was necessary to extract the parasitic Z-elements. The metal-semiconductor ohmic contacts were modeled as a transmission line, and, each element of the transmission model was determined. The resultant modeling described the highly resistive contacts with a good accuracy and enabled the determination of the intrinsic circuit models. Application of the model can be extended to a general field-effect transistor with highly resistive ohmic contacts.

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