Papers by Keyword: 4H-SiC MOS

Abstract: Effects of NO and forming gas annealing treatment on the interface quality and reliability of 4H-SiC MOS were systematically studied by low temperature conductance measurements in combination with time-zero dielectric breakdown and time-dependent dielectric breakdown methods. The interface trap density (D_it) showed no obvious reduction after forming gas annealing, and the values of D_it decreased significantly after combined NO and forming gas annealing treatment. The F-N barrier height, electric field to breakdown (E_bd) and charge to breakdown (Q_bd) of the MOS structure increased from 2.42 eV, 10 MV/cm, 1mC/cm² to 2.62 eV, 10.7 MV/cm, 78mC/cm² after forming gas annealing. The values of F-N barrier height, E_bd and Q_bd for MOS capacitors with combined NO and forming gas annealing treatment are 2.69 eV, 10.2 MV/cm, and 24mC/cm². These results suggest that forming gas annealing is more effective in reliability improvement. While when considering the interface trap density, it seems that combined NO and forming gas annealing treatment is a better choice.

Abstract: Temperature dependent capacitance-voltage (C-V) and constant capacitance transient spectroscopy (CCDLTS) measurements have been performed to investigate the role of N in improving the transport properties of 4H-SiC MOS transistors. The higher channel mobility in the N pre-implanted transistors is due at least in part to activation of a small fraction of the implanted N near the SiO₂/SiC interface as donors in SiC during oxidation, thus reducing the effects of interface trapping. In addition, the absence of oxidation-induced near-interface defects, which were observed in NO-annealed capacitors, may contribute to the improved mobility in N pre-implanted transistors.

Abstract: The effect of incorporation of cesium with implantation on the electrical characteristics of SiO2/4H-SiC interface has been evaluated using MOS capacitors. With a cesium dosage of 1012 and 3x1012 cm-2 on deposited oxide re-oxidized in steam, effective oxide charge densities of - 1.4x1012 and -7.5x1011 cm-2 respectively were extracted and a cesium implant activation percentage of 33% was estimated from flatband voltage shift. Also, corresponding interfacial state densities of 2.5x1013 and 1.8x1013 cm-2-eV-1 near the conduction band edge were extracted from High-Low frequency C-V technique, showing a decreasing Dit with increasing Cs dosage.