3.6 m cm2, 1726 V 4H-SiC normally-off trenched-and-implanted vertical JFETs and circuit applications

Abstract

A normally-off 4H-SiC trenched-and-implanted vertical JFET (TI-VJFET) with a low specific on-resistance has been demonstrated. The low specific on-resistance (R_{on_sp}) of 3.6 mΩ cm² is achieved for a blocking voltage (V_bl) up to 1726 V by eliminating the internal lateral JFET gates. The TI-VJFET technology developed is advantageous in comparison to other reported VJFET technologies because it eliminates the need for epitaxial regrowth in the middle of device fabrication, only one mask requires critical alignment throughout device fabrication, and it provides intrinsically a much lower specific on-resistance owing to the elimination of internal lateral JFET gates. The V_bl²/R_{on_sp} value of 827 MW/cm² for the TI-VJFET substantially surpasses all past records of both unipolar and bipolar SiC power switches. Multi-cell TI-VJFETs have been packaged and tested in an inductively loaded half-bridge inverter. Switching characteristics are reported. A 50 A Darlington transistor has also been developed using the TI-VJFET switches and results are given.