Fully ion implanted MESFETs in bulk semi-insulating 4H-SiC

摘要

MESFETs (n-channel) were fabricated in semi-insulating bulk 4H-SiC by ion implantation of both the source/drain and the channel regions, using an aluminum Schottky gate metal and nickel ohmic contacts. Nitrogen ion implantation was performed at room temperature to a depth of 300 nm at a volumetric concentration of 6X10~(17) cm~(-3) for the channel region and 2X10~(19) cm~(-3) for the source/drain. The implants were activated by annealing at 1450deg C for 15 min using an AlN encapsulant. The bulk mobility of the channel implant was found to be 240 cm~2/V s, while the effective channel mobility of the devices was measured to be less than 58 cm~2/V s. For a typical device with a 2-#mu#m gate length, the pinch-off voltage was 18 V, and the drain saturation current was approximately 40 mA. Devices exhibited only a small change in their DC characteristics over the temperature range 25-350 deg C.