950V, 8.7mohm-cm2 high speed 4H-SiC power DMOSFETs

Fabrication and characteristics of high voltage, high speed DMOSFETs in 4H-SiC are presented. The devices were built on 1.2x10(16) cm(-3) doped, 6 mu m thick n-type epilayer grown on a n(+) 4H-SiC substrate. A specific on-resistance of 8.7 m Omega cm(2) and a blocking voltage of 950 V were measured. Device characteristics were measured for temperatures up to 300 degrees C. An increase of specific on-resistance by 35% observed at 300 degrees C, when compared to the value at room temperature. This is due to a negative shift in MOS threshold voltage, which decreases the MOS channel resistance at elevated temperatures. This effect cancels out the increase in drift layer resistance due to a decrease in bulk electron mobility at elevated temperature, resulting in a temperature stable on-resistance. The device operation at temperatures up to 300 degrees C and high speed switching results are also reported in this paper.