High electron mobility achieved in n‐channel 4H‐SiC MOSFETs oxidized in the presence of nitrogen

Abstract

AbstractTwo types of nitrided n‐4H‐SiC MOSFETs have been investigated; the p‐type 4H‐SiC epilayer is either oxidized in the presence of N2O or an N‐/Al‐co‐implanted, surface‐near layer is over‐oxidized. The electrical parameters of these MOSFETs are determined and compared. We have investigated the temperature‐dependence of the threshold voltage VT and determined the effective mobility μeff and the field effect mobility μFE. Based on Hall effect measurements, we determined independently the free electron areal density ns, the Hall mobility μH and the differential Hall mobility μH,diff. The density of interface states Dit is obtained from the Hall effect, the temperature‐dependent VT and the conductance method. The stability of both types of MOSFETs is tested under stress (VG = ±25 V) at T = 295 K and T = 375 K. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)