This work deals with the assessment of gate dielectric for 4H-SiC MOSFETs using technology based two-dimensional numerical\ncomputer simulations. Results are studied for variety of gate dielectric candidates with varying thicknesses using well-known\nFowler-Nordheim tunnelingmodel.Compared to conventional SiO2 as a gate dielectric for 4H-SiCMOSFETs, high-k gate dielectric\nsuch as HfO2 reduces significantly the amount of electric field in the gate dielectric with equal gate dielectric thickness and hence\nthe overall gate current density. High-k gate dielectric further reduces the shift in the threshold voltage with varying dielectric\nthicknesses, thus leading to better process margin and stable device operating behavior. For fixed dielectric thickness, a total shift in\nthe threshold voltage of about 2.5Vhas been observedwith increasing dielectric constant fromSiO2 (k = 3.9) toHfO2 (k = 25). This\nfurther results in higher transconductance of the device with the increase of the dielectric constant fromSiO2 toHfO2. Furthermore,\n4H-SiCMOSFETs are found to be more sensitive to the shift in the threshold voltage with conventional SiO2 as gate dielectric than\nhigh-k dielectric with the presence of interface state charge density that is typically observed at the interface of dielectric and 4H-SiC\nMOS surface.
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