Papers by Author: Alberto F. Basile

Abstract: The electrical properties of the SiO₂/SiC interface fabricated by sodium-enhanced oxidation (SEO) of n-type 4H-SiC were studied by temperature-dependent C-V and constant-capacitance deep level transient spectroscopy (CCDLTS). With the exception of near-interface traps in the SiC epi-layer, which are not present in the SEO samples, the trap species observed in SEO capacitors are the same as those observed in both standard-oxidized and NO-annealed MOS capacitors. Total electron trapping in accumulation is comparable in SEO and NO-annealed capacitors; however, the traps in SEO capacitors are located at the interface whereas tunneling into oxide traps is observed in NO-annealed samples. A series of bias-temperature stress tests show that electron trapping is essentially unchanged when mobile sodium ions are moved toward the interface. The improved mobility attained by this process compared to NO annealing may be due to the absence of near-interface SiC traps in SEO samples.

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 electrical properties of the SiC/SiO2 interface resulting from oxidation of the n-type 6H-SiC polytype were studied by hi-lo CV, temperature dependent CV and constant capacitance deep level transient spectroscopy (CCDLTS) techniques. Several trap species differing in energy and capture cross section were identified. A trap distribution at 0.5 eV below the 6H-SiC conduction band energy and a shallower density of states in both the 6H and 4H polytyes are passivated by post-oxidation NO annealing. However, other ultra-shallow and deeper defect distributions remain after nitridation. The latter may originate from semiconductor traps.