Detection of near-interface traps in NO annealed 4H-SiC metal oxide semiconductor capacitors combining different electrical characterization methods

Abstract

Fast near-interface (NI) traps have recently been suggested to be the main cause for poor inversion channel mobility in nitrided SiC metal-oxide-semiconductor-field-effect-transistors. Combining capacitance, conductance, and thermal dielectric relaxation current (TDRC) analysis at low temperatures of nitrided SiC MOS capacitors, we observe two categories of fast and slow near-interface traps at the SiO2/4H-SiC interface. TDRC reveals a suppression of slow near-interface traps after nitridation. Capacitance and conductance analysis reveals a high density of fast NI traps close to the SiC conduction band edge that are enhanced by nitridation. The very fast response of NI traps prevents them from detection using TDRC or deep level transient spectroscopy.