Characterization of Device Parameters in HighTemperature MetalOxide Semiconductor FieldEffect Transistors in SiC Thin Films

Both inversion- and depletion-mode n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) have been fabricated on ?>-SiC thin films grown by chemical-vapor deposition. The inversion-mode devices were made on in situ doped (A1) p-type ?>-SiC(100) thin films grown on Si(100) substrates. The depletion-mode MOSFETs were made on n-type ?>-SiC( 111) thin films grown on the Si(0001) face of a 6H ?>-SiC substrates. Stable saturation and low subthreshold currents were achieved at drain-source voltages exceeding 5 and 25 V for the inversion-mode and depletion-mode devices, respectively. The transconductance increased with temperat0ure up to 673 K for the short-gate-length devices, of either mode, and then decreased with further increases in temperature. It is proposed that the transconductances and threshold voltages for the inversion-mode devices are greatly affected by minority-carrier injection from the source. Stable transistor action was observed for both types of devices at temperatures up to 823 K, with the depletion-mode devices operating very well up to 923 K.