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U. Schmid, S.T. Sheppard, W. Wondrak:
"Circular and linear enhancement-mode 6H-SiC MOSFETs for high temperature applications";
Journal of Electronic Materials, Vol. 28, Sonderausgabe "III-V Nitrides and SiC" (1999), 3; 148 - 153.

Direct current measurements are performed up to 673K at circular and linear (shown in parenthesis) enhancement-mode metal oxide semiconductor field effect transistors (MOSFETs). These devices are fabricated on a p-type 6H-SiC epitaxial layer with a doping concentration NA ≈ 1 × 1016 cm−1. The n+ source/drain regions and the p+ regions for the channel stops are achieved by ion implantation of nitrogen and aluminum, respectively. Both MOSFET geometries show excellent output characteristics with a good saturation behavior even at elevated temperatures. The inversion layer mobility μn extracted in the linear region is 38 cm2·V−1·s−1 (35 cm2·V−1·s−1) and reveals a weak dependence on temperature with a maximum of 46 cm2·V−1·s−1 (42 cm2·V−1·s−1) at about 473K. Regarding the transfer characteristics, the drain current ID can be well modulated by the gate-source voltage VGS resulting in an Ion/Loff-ratio of 108 (108) at 303K and 105 (106) at 673K. In the subthreshold regime, ID can be pinched off well below 10 pA with a subthreshold swing of 150 mV/decade (155 mV/decade) at room temperature. The threshold voltage VT as a function of temperature shows two linear sections with negative temperature coefficients of −6.8 mV·K−1 (−6.8 mV·K−1) from 303 to 423K and −2.5 mV·K−1 (−2.0 mV·K−1) from 423 to 673K. By measuring VT as a function of bulk-source voltage VBS at different temperatures, NA can be directly estimated at a transistor and gives 9.6 × 1015 cm−3 (9.8 × 1015 cm−3). The measured bulk Fermi potential Φf of the p-type epitaxial layer deviates less than 10% from the calculated value at a given temperature.

http://dx.doi.org/10.1007/s11664-999-0005-2