Electrical characterization of 6H–SiC enhancement-mode MOSFETs at high temperatures

Linear, small-signal enhancement-mode MOSFETs are fabricated in p-type 6H–SiC. Ion implantation of nitrogen and aluminum are used to form the n+-regions for the source/drain contacts and the channel-stop, respectively. Direct current measurements were performed up to 673 K, revealing a drain-to-source saturation current IDSS of 1.53 mA mm−1 at VDS=+10 V and VGS=+9 V, a transconductance in saturation of 0.56 mS mm−1 at VGS=+9 V and a subthreshold slope of 170 mV per decade at room temperature. The excellent high temperature behavior is demonstrated by an ION/IOff ratio of 105 at 673 K (108 at 303 K) and low leakage currents (<10 pA) below threshold up to 523 K. The inversion layer mobility of the electrons μn is 40 cm2 V−1 s−1 at room temperature, having a thermally activated region up to 423 K with maximum of 44 cm2 V−1 s−1 before decreasing by phonon scattering.