Analysis of geometrical magnetoresistance Al0.35Ga0.65N/GaN MODFETs

Geometrical magnetoresistance measurements can be used to obtain mobility and carrier concentration in field effect transistor structures. While easily implemented, the accuracy of extracted parameters can be adversely affected by high parasitic resistance rising from ohmic contacts and/or ungated channel access regions. We present here a parameter extraction method for MODFET structures that, accounts for parasitic elements, allowing accurate extraction of mobility-concentration profiles. To demonstrate the applicability of the method, and the deleterious effect of series resistance, we apply the method to an Al_0.35Ga_0.65N/GaN MODFET and compare, the results obtained to those obtained by neglecting the effect of parasitic contact resistance.