ALPHA-SIC BURIED-GATE JUNCTION FIELD-EFFECT TRANSISTORS

We report the results of an experimental study on alpha-SiC buried-gate junction field effect transistors operating in the temperature range from 24 to 400-degrees-C. The epitaxial structure used for fabrication of these devices employs a nitrogen-doped hexagonal alpha-SiC layer grown on a p-type aluminum-doped alpha-SiC film. Epitaxial layers were grown on the silicon face of unintentionally doped n-type alpha-SiC substrates. The current in the channel is modulated using the p-type layer as a gate. Fabricated devices with a 4-mu-m gate length have a maximum transconductance (g(m)) of 17 mS mm-1 and a drain saturation current (I(DSS)) of 450 mA mm-1 at room temperature. This value of the transconductance is the highest reported for devices of similar structure. Devices are completely pinched off at a gate voltage of -40 V. The device transconductance drops with increasing temperature owing to the decrease in electron mobility. The values of electron mobility at elevated temperatures derived from the measured transconductances and drain conductances are in agreement with independently measured Hall data.