Quantitative Investigation of Near Interface Traps in 4H-SiC MOSFETs via Drain Current Deep Level Transient Spectroscopy

Drain current DLTS (I D -DLTS) and Hall effect measurements were carried out on two types of 4H-SiC n-MOSFETs, one with a post oxidation annealing (POA) in NO and one in O 2 atmosphere. Hall effect measurements show a reduction of D it by POA in NO compared to POA in O 2 and, as a consequence, a higher inversion charge carrier density, while the Hall mobility is only weakly affected by the introduction of nitrogen during POA. Based on I D -DLTS we provide a method for a quantitative and selective investigation of near interface traps (NITs) in the oxide. It is shown that POA in NO strongly reduces the density of NITs.