Second-Order Effects on 4H-SiC Lateral MOSFETs Characteristics up to 773 K

An analysis of 4H-SiC CMOSFETs electrical characteristics is reported up to a temperature of 773 K taking into account the effects of the channel lengths, i.e., 2 and 6 μm , and of the physical parameters. Even though the threshold voltage and the channel mobility have similar dependencies on the geometry and temperature, they are described by quite different phenomena. For NMOSFET, the threshold voltage has a further reduction with the channel shortening and with the temperature due to 4H-SiC/SiO2 interface defects, instead its maximum channel mobility of around 21.75 cm2/V/s results almost the same up to 723K but then drastically reduces to 14.28 cm2/V/s due to lattice vibration scattering. On the other hand, PMOSFET shows a hump of the threshold voltage with the reduction of the channel length, ascribing to a reverse short-channel effect, whereas the channel mobility is strongly affected by p-type parasitic series resistances. Due to the concomitant effects of the threshold voltage and of the channel mobility, the current increases with the temperature up to the range of [523-623] K, depending on the channel size, but then decreases, avoiding the thermal run-away effect.