Impact of Al Doping Concentration at Channel Region on Mobility and Threshold Voltage Instability in 4H-SiC Trench N-MOSFETs

Abstract

The effect of Al doping concentration (NA) at channel regions ranging from 1.0×1017 to 4.0×1017 cm-3 on the effective channel mobility of electron (μeff) and the threshold voltage (Vth) instability under the positive bias-temperature-stress conditions has been investigated througu the use of trench-gate 4H-SiC MOSFETs with m-face (1-100) channel regions. It was found that μeff degraded with an increase in NA. On the other hand, the increase of NA enlarged the Vth instability. These results indicate that NA has a large impact not only on the Vth value but also on the channel resistance and reliability in 4H-SiC trench MOSFETs.